CC Animation: Merge LayerAnimationController into ElementAnimations.

cc/animation/element_animations_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/animation/element_animations.h"
 
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/animation_player.h"
 #include "cc/animation/animation_timeline.h"
+#include "cc/animation/keyframed_animation_curve.h"
+#include "cc/animation/scroll_offset_animation_curve.h"
+#include "cc/animation/transform_operations.h"
 #include "cc/test/animation_test_common.h"
 #include "cc/test/animation_timelines_test_common.h"
+#include "ui/gfx/geometry/box_f.h"
 
 namespace cc {
 namespace {
 
+using base::TimeDelta;
+using base::TimeTicks;
+
+static base::TimeTicks TicksFromSecondsF(double seconds) {
+  return base::TimeTicks::FromInternalValue(seconds *
+                                            base::Time::kMicrosecondsPerSecond);
+}
+
+// An ElementAnimations cannot be ticked at 0.0, since an animation
+// with start time 0.0 is treated as an animation whose start time has
+// not yet been set.
+const TimeTicks kInitialTickTime = TicksFromSecondsF(1.0);
+
 class ElementAnimationsTest : public AnimationTimelinesTest {
  public:
   ElementAnimationsTest() {}
   ~ElementAnimationsTest() override {}
 };
 
 // See animation_player_unittest.cc for integration with AnimationPlayer.
 
 TEST_F(ElementAnimationsTest, AttachToLayerInActiveTree) {
   // Set up the layer which is in active tree for main thread and not
@@ skipping 167 matching lines @@
            element_animations_impl->players_list().head();
        node != element_animations_impl->players_list().end();
        node = node->next()) {
     const AnimationPlayer* player_impl = node->value();
     EXPECT_TRUE(timeline_->GetPlayerById(player_impl->id()));
     ++list_size_after;
   }
   EXPECT_EQ(2, list_size_after);
 }
 
+TEST_F(ElementAnimationsTest, SyncNewAnimation) {
+  auto animations_impl = ElementAnimations::Create();
+  animations_impl->set_needs_active_value_observations(true);
+
+  auto animations = ElementAnimations::Create();
+  animations->set_needs_active_value_observations(true);
+
+  EXPECT_FALSE(animations_impl->GetAnimation(TargetProperty::OPACITY));
+
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+  EXPECT_FALSE(animations_impl->needs_to_start_animations_for_testing());
+
+  int animation_id =
+      AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(animations_impl->needs_to_start_animations_for_testing());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+}
+
+TEST_F(ElementAnimationsTest,
+       SyncScrollOffsetAnimationRespectsHasSetInitialValue) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_FALSE(animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET));
+
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+  EXPECT_FALSE(animations_impl->needs_to_start_animations_for_testing());
+
+  gfx::ScrollOffset initial_value(100.f, 300.f);
+  gfx::ScrollOffset provider_initial_value(150.f, 300.f);
+  gfx::ScrollOffset target_value(300.f, 200.f);
+
+  client_impl_.SetScrollOffsetForAnimation(provider_initial_value);
+
+  // Animation with initial value set.
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve_fixed(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+  curve_fixed->SetInitialValue(initial_value);
+  const int animation1_id = 1;
+  std::unique_ptr<Animation> animation_fixed(Animation::Create(
+      std::move(curve_fixed), animation1_id, 0, TargetProperty::SCROLL_OFFSET));
+  animations->AddAnimation(std::move(animation_fixed));
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_VECTOR2DF_EQ(initial_value,
+                      animations_impl->GetAnimationById(animation1_id)
+                          ->curve()
+                          ->ToScrollOffsetAnimationCurve()
+                          ->GetValue(base::TimeDelta()));
+
+  // Animation without initial value set.
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+  const int animation2_id = 2;
+  std::unique_ptr<Animation> animation(Animation::Create(
+      std::move(curve), animation2_id, 0, TargetProperty::SCROLL_OFFSET));
+  animations->AddAnimation(std::move(animation));
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_VECTOR2DF_EQ(provider_initial_value,
+                      animations_impl->GetAnimationById(animation2_id)
+                          ->curve()
+                          ->ToScrollOffsetAnimationCurve()
+                          ->GetValue(base::TimeDelta()));
+}
+
+// If an animation is started on the impl thread before it is ticked on the main
+// thread, we must be sure to respect the synchronized start time.
+TEST_F(ElementAnimationsTest, DoNotClobberStartTimes) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_FALSE(animations_impl->GetAnimation(TargetProperty::OPACITY));
+
+  int animation_id =
+      AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Synchronize the start times.
+  EXPECT_EQ(1u, events->events_.size());
+  animations->NotifyAnimationStarted(events->events_[0]);
+  EXPECT_EQ(animations->GetAnimationById(animation_id)->start_time(),
+            animations_impl->GetAnimationById(animation_id)->start_time());
+
+  // Start the animation on the main thread. Should not affect the start time.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, nullptr);
+  EXPECT_EQ(animations->GetAnimationById(animation_id)->start_time(),
+            animations_impl->GetAnimationById(animation_id)->start_time());
+}
+
+TEST_F(ElementAnimationsTest, UseSpecifiedStartTimes) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  int animation_id =
+      AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+
+  const TimeTicks start_time = TicksFromSecondsF(123);
+  animations->GetAnimation(TargetProperty::OPACITY)->set_start_time(start_time);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Synchronize the start times.
+  EXPECT_EQ(1u, events->events_.size());
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  EXPECT_EQ(start_time,
+            animations->GetAnimationById(animation_id)->start_time());
+  EXPECT_EQ(animations->GetAnimationById(animation_id)->start_time(),
+            animations_impl->GetAnimationById(animation_id)->start_time());
+
+  // Start the animation on the main thread. Should not affect the start time.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, nullptr);
+  EXPECT_EQ(start_time,
+            animations->GetAnimationById(animation_id)->start_time());
+  EXPECT_EQ(animations->GetAnimationById(animation_id)->start_time(),
+            animations_impl->GetAnimationById(animation_id)->start_time());
+}
+
+// Tests that animationss activate and deactivate as expected.
+TEST_F(ElementAnimationsTest, Activation) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  AnimationHost* host = client_.host();
+  AnimationHost* host_impl = client_impl_.host();
+
+  auto events = host_impl_->CreateEvents();
+
+  EXPECT_EQ(1u, host->all_element_animations_for_testing().size());
+  EXPECT_EQ(1u, host_impl->all_element_animations_for_testing().size());
+
+  // Initially, both animationss should be inactive.
+  EXPECT_EQ(0u, host->active_element_animations_for_testing().size());
+  EXPECT_EQ(0u, host_impl->active_element_animations_for_testing().size());
+
+  AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+  // The main thread animations should now be active.
+  EXPECT_EQ(1u, host->active_element_animations_for_testing().size());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  // Both animationss should now be active.
+  EXPECT_EQ(1u, host->active_element_animations_for_testing().size());
+  EXPECT_EQ(1u, host_impl->active_element_animations_for_testing().size());
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(1u, events->events_.size());
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  EXPECT_EQ(1u, host->active_element_animations_for_testing().size());
+  EXPECT_EQ(1u, host_impl->active_element_animations_for_testing().size());
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, nullptr);
+  EXPECT_EQ(1u, host->active_element_animations_for_testing().size());
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, nullptr);
+  EXPECT_EQ(Animation::FINISHED,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_EQ(1u, host->active_element_animations_for_testing().size());
+
+  events = host_impl_->CreateEvents();
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1500));
+  animations_impl->UpdateState(true, events.get());
+
+  EXPECT_EQ(
+      Animation::WAITING_FOR_DELETION,
+      animations_impl->GetAnimation(TargetProperty::OPACITY)->run_state());
+  // The impl thread animations should have de-activated.
+  EXPECT_EQ(0u, host_impl->active_element_animations_for_testing().size());
+
+  EXPECT_EQ(1u, events->events_.size());
+  animations->NotifyAnimationFinished(events->events_[0]);
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1500));
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_EQ(Animation::WAITING_FOR_DELETION,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  // The main thread animations should have de-activated.
+  EXPECT_EQ(0u, host->active_element_animations_for_testing().size());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->has_any_animation());
+  EXPECT_FALSE(animations_impl->has_any_animation());
+  EXPECT_EQ(0u, host->active_element_animations_for_testing().size());
+  EXPECT_EQ(0u, host_impl->active_element_animations_for_testing().size());
+}
+
+TEST_F(ElementAnimationsTest, SyncPause) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_FALSE(animations_impl->GetAnimation(TargetProperty::OPACITY));
+
+  // Two steps, three ranges: [0-1) -> 0.2, [1-2) -> 0.3, [2-3] -> 0.4.
+  const double duration = 3.0;
+  const int animation_id = AddOpacityStepsToElementAnimations(
+      animations.get(), duration, 0.2f, 0.4f, 2);
+
+  // Set start offset to be at the beginning of the second range.
+  animations->GetAnimationById(animation_id)
+      ->set_time_offset(TimeDelta::FromSecondsD(1.01));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  TimeTicks time = kInitialTickTime;
+
+  // Start the animations on each animations.
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(time);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(1u, events->events_.size());
+
+  animations->Animate(time);
+  animations->UpdateState(true, nullptr);
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_EQ(Animation::RUNNING,
+            animations->GetAnimationById(animation_id)->run_state());
+
+  EXPECT_EQ(0.3f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(0.3f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_EQ(kInitialTickTime,
+            animations->GetAnimationById(animation_id)->start_time());
+  EXPECT_EQ(kInitialTickTime,
+            animations_impl->GetAnimationById(animation_id)->start_time());
+
+  // Pause the animation at the middle of the second range so the offset
+  // delays animation until the middle of the third range.
+  animations->PauseAnimation(animation_id, TimeDelta::FromSecondsD(1.5));
+  EXPECT_EQ(Animation::PAUSED,
+            animations->GetAnimationById(animation_id)->run_state());
+
+  // The pause run state change should make it to the impl thread animations.
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  // Advance time so it stays within the first range.
+  time += TimeDelta::FromMilliseconds(10);
+  animations->Animate(time);
+  animations_impl->Animate(time);
+
+  EXPECT_EQ(Animation::PAUSED,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  // Opacity value doesn't depend on time if paused at specified time offset.
+  EXPECT_EQ(0.4f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(0.4f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, DoNotSyncFinishedAnimation) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  EXPECT_FALSE(animations_impl->GetAnimation(TargetProperty::OPACITY));
+
+  int animation_id =
+      AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[0].type);
+
+  // Notify main thread animations that the animation has started.
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  // Complete animation on impl thread.
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime + TimeDelta::FromSeconds(1));
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::FINISHED, events->events_[0].type);
+
+  animations->NotifyAnimationFinished(events->events_[0]);
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromSeconds(2));
+  animations->UpdateState(true, nullptr);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->GetAnimationById(animation_id));
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id));
+}
+
+// Ensure that a finished animation is eventually deleted by both the
+// main-thread and the impl-thread animationss.
+TEST_F(ElementAnimationsTest, AnimationsAreDeleted) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  AddOpacityTransitionToElementAnimations(animations.get(), 1.0, 0.0f, 1.0f,
+                                          false);
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, nullptr);
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  animations_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations_impl->UpdateState(true, events.get());
+
+  // There should be a STARTED event for the animation.
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[0].type);
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_FALSE(host_->animation_waiting_for_deletion());
+  EXPECT_FALSE(host_impl_->animation_waiting_for_deletion());
+
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(2000));
+  animations_impl->UpdateState(true, events.get());
+
+  EXPECT_TRUE(host_impl_->animation_waiting_for_deletion());
+
+  // There should be a FINISHED event for the animation.
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::FINISHED, events->events_[0].type);
+
+  // Neither animations should have deleted the animation yet.
+  EXPECT_TRUE(animations->GetAnimation(TargetProperty::OPACITY));
+  EXPECT_TRUE(animations_impl->GetAnimation(TargetProperty::OPACITY));
+
+  animations->NotifyAnimationFinished(events->events_[0]);
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(host_->animation_waiting_for_deletion());
+
+  animations->PushPropertiesTo(animations_impl.get());
+
+  // Both animationss should now have deleted the animation. The impl animations
+  // should have deleted the animation even though activation has not occurred,
+  // since the animation was already waiting for deletion when
+  // PushPropertiesTo was called.
+  EXPECT_FALSE(animations->has_any_animation());
+  EXPECT_FALSE(animations_impl->has_any_animation());
+}
+
+// Tests that transitioning opacity from 0 to 1 works as expected.
+
+static std::unique_ptr<Animation> CreateAnimation(
+    std::unique_ptr<AnimationCurve> curve,
+    int group_id,
+    TargetProperty::Type property) {
+  return Animation::Create(std::move(curve), 0, group_id, property);
+}
+
+static const AnimationEvent* GetMostRecentPropertyUpdateEvent(
+    const AnimationEvents* events) {
+  const AnimationEvent* event = 0;
+  for (size_t i = 0; i < events->events_.size(); ++i)
+    if (events->events_[i].type == AnimationEvent::PROPERTY_UPDATE)
+      event = &events->events_[i];
+
+  return event;
+}
+
+TEST_F(ElementAnimationsTest, TrivialTransition) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+  animations->AddAnimation(std::move(to_add));
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+  animations->Animate(kInitialTickTime);
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  // A non-impl-only animation should not generate property updates.
+  const AnimationEvent* event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+}
+
+TEST_F(ElementAnimationsTest, TrivialTransitionOnImpl) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  to_add->set_is_impl_only(true);
+
+  animations_impl->AddAnimation(std::move(to_add));
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(1u, events->events_.size());
+  const AnimationEvent* start_opacity_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_EQ(0.f, start_opacity_event->opacity);
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(1.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(2u, events->events_.size());
+  const AnimationEvent* end_opacity_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_EQ(1.f, end_opacity_event->opacity);
+}
+
+TEST_F(ElementAnimationsTest, TrivialTransformOnImpl) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  // Choose different values for x and y to avoid coincidental values in the
+  // observed transforms.
+  const float delta_x = 3;
+  const float delta_y = 4;
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve(
+      KeyframedTransformAnimationCurve::Create());
+
+  // Create simple TRANSFORM animation.
+  TransformOperations operations;
+  curve->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations, nullptr));
+  operations.AppendTranslate(delta_x, delta_y, 0);
+  curve->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::TRANSFORM));
+  animation->set_is_impl_only(true);
+  animations_impl->AddAnimation(std::move(animation));
+
+  // Run animation.
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(gfx::Transform(),
+            client_impl_.GetTransform(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(1u, events->events_.size());
+  const AnimationEvent* start_transform_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  ASSERT_TRUE(start_transform_event);
+  EXPECT_EQ(gfx::Transform(), start_transform_event->transform);
+  EXPECT_TRUE(start_transform_event->is_impl_only);
+
+  gfx::Transform expected_transform;
+  expected_transform.Translate(delta_x, delta_y);
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(expected_transform,
+            client_impl_.GetTransform(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(2u, events->events_.size());
+  const AnimationEvent* end_transform_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_EQ(expected_transform, end_transform_event->transform);
+  EXPECT_TRUE(end_transform_event->is_impl_only);
+}
+
+TEST_F(ElementAnimationsTest, FilterTransition) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<KeyframedFilterAnimationCurve> curve(
+      KeyframedFilterAnimationCurve::Create());
+
+  FilterOperations start_filters;
+  start_filters.Append(FilterOperation::CreateBrightnessFilter(1.f));
+  curve->AddKeyframe(
+      FilterKeyframe::Create(base::TimeDelta(), start_filters, nullptr));
+  FilterOperations end_filters;
+  end_filters.Append(FilterOperation::CreateBrightnessFilter(2.f));
+  curve->AddKeyframe(FilterKeyframe::Create(base::TimeDelta::FromSecondsD(1.0),
+                                            end_filters, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::FILTER));
+  animations->AddAnimation(std::move(animation));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(start_filters,
+            client_.GetFilters(layer_id_, LayerTreeType::ACTIVE));
+  // A non-impl-only animation should not generate property updates.
+  const AnimationEvent* event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1u, client_.GetFilters(layer_id_, LayerTreeType::ACTIVE).size());
+  EXPECT_EQ(FilterOperation::CreateBrightnessFilter(1.5f),
+            client_.GetFilters(layer_id_, LayerTreeType::ACTIVE).at(0));
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(end_filters, client_.GetFilters(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+}
+
+TEST_F(ElementAnimationsTest, FilterTransitionOnImplOnly) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<KeyframedFilterAnimationCurve> curve(
+      KeyframedFilterAnimationCurve::Create());
+
+  // Create simple FILTER animation.
+  FilterOperations start_filters;
+  start_filters.Append(FilterOperation::CreateBrightnessFilter(1.f));
+  curve->AddKeyframe(
+      FilterKeyframe::Create(base::TimeDelta(), start_filters, nullptr));
+  FilterOperations end_filters;
+  end_filters.Append(FilterOperation::CreateBrightnessFilter(2.f));
+  curve->AddKeyframe(FilterKeyframe::Create(base::TimeDelta::FromSecondsD(1.0),
+                                            end_filters, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::FILTER));
+  animation->set_is_impl_only(true);
+  animations_impl->AddAnimation(std::move(animation));
+
+  // Run animation.
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(start_filters,
+            client_impl_.GetFilters(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(1u, events->events_.size());
+  const AnimationEvent* start_filter_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_TRUE(start_filter_event);
+  EXPECT_EQ(start_filters, start_filter_event->filters);
+  EXPECT_TRUE(start_filter_event->is_impl_only);
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(end_filters,
+            client_impl_.GetFilters(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(2u, events->events_.size());
+  const AnimationEvent* end_filter_event =
+      GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_TRUE(end_filter_event);
+  EXPECT_EQ(end_filters, end_filter_event->filters);
+  EXPECT_TRUE(end_filter_event->is_impl_only);
+}
+
+TEST_F(ElementAnimationsTest, ScrollOffsetTransition) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  gfx::ScrollOffset initial_value(100.f, 300.f);
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::SCROLL_OFFSET));
+  animation->set_needs_synchronized_start_time(true);
+  animations->AddAnimation(std::move(animation));
+
+  client_impl_.SetScrollOffsetForAnimation(initial_value);
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET));
+  TimeDelta duration =
+      animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET)
+          ->curve()
+          ->Duration();
+  EXPECT_EQ(duration, animations->GetAnimation(TargetProperty::SCROLL_OFFSET)
+                          ->curve()
+                          ->Duration());
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(initial_value,
+            client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(initial_value,
+            client_impl_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  // Scroll offset animations should not generate property updates.
+  const AnimationEvent* event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->NotifyAnimationStarted(events->events_[0]);
+  animations->Animate(kInitialTickTime + duration / 2);
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_VECTOR2DF_EQ(
+      gfx::Vector2dF(200.f, 250.f),
+      client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime + duration / 2);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(
+      gfx::Vector2dF(200.f, 250.f),
+      client_impl_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations_impl->Animate(kInitialTickTime + duration);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(target_value, client_impl_.GetScrollOffset(
+                                        layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->Animate(kInitialTickTime + duration);
+  animations->UpdateState(true, nullptr);
+  EXPECT_VECTOR2DF_EQ(
+      target_value, client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+TEST_F(ElementAnimationsTest, ScrollOffsetTransitionOnImplOnly) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  gfx::ScrollOffset initial_value(100.f, 300.f);
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+  curve->SetInitialValue(initial_value);
+  double duration_in_seconds = curve->Duration().InSecondsF();
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::SCROLL_OFFSET));
+  animation->set_is_impl_only(true);
+  animations_impl->AddAnimation(std::move(animation));
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(initial_value,
+            client_impl_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  // Scroll offset animations should not generate property updates.
+  const AnimationEvent* event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  TimeDelta duration = TimeDelta::FromMicroseconds(
+      duration_in_seconds * base::Time::kMicrosecondsPerSecond);
+
+  animations_impl->Animate(kInitialTickTime + duration / 2);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(
+      gfx::Vector2dF(200.f, 250.f),
+      client_impl_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations_impl->Animate(kInitialTickTime + duration);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(target_value, client_impl_.GetScrollOffset(
+                                        layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+}
+
+// Ensure that when the impl animations doesn't have a value provider,
+// the main-thread animations's value provider is used to obtain the intial
+// scroll offset.
+TEST_F(ElementAnimationsTest, ScrollOffsetTransitionNoImplProvider) {
+  CreateTestLayer(false, false);
+  CreateTestImplLayer(LayerTreeType::PENDING);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_TRUE(animations_impl->needs_pending_value_observations());
+  EXPECT_FALSE(animations_impl->needs_active_value_observations());
+
+  auto events = host_impl_->CreateEvents();
+
+  gfx::ScrollOffset initial_value(500.f, 100.f);
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve), 1, 0, TargetProperty::SCROLL_OFFSET));
+  animation->set_needs_synchronized_start_time(true);
+  animations->AddAnimation(std::move(animation));
+
+  client_.SetScrollOffsetForAnimation(initial_value);
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET));
+  TimeDelta duration =
+      animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET)
+          ->curve()
+          ->Duration();
+  EXPECT_EQ(duration, animations->GetAnimation(TargetProperty::SCROLL_OFFSET)
+                          ->curve()
+                          ->Duration());
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(initial_value,
+            client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_EQ(gfx::ScrollOffset(),
+            client_impl_.GetScrollOffset(layer_id_, LayerTreeType::PENDING));
+
+  animations_impl->Animate(kInitialTickTime);
+
+  EXPECT_TRUE(animations_impl->HasActiveAnimation());
+  EXPECT_EQ(initial_value,
+            client_impl_.GetScrollOffset(layer_id_, LayerTreeType::PENDING));
+
+  CreateTestImplLayer(LayerTreeType::ACTIVE);
+
+  animations_impl->UpdateState(true, events.get());
+  DCHECK_EQ(1UL, events->events_.size());
+
+  // Scroll offset animations should not generate property updates.
+  const AnimationEvent* event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->NotifyAnimationStarted(events->events_[0]);
+  animations->Animate(kInitialTickTime + duration / 2);
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_VECTOR2DF_EQ(
+      gfx::Vector2dF(400.f, 150.f),
+      client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime + duration / 2);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(
+      gfx::Vector2dF(400.f, 150.f),
+      client_impl_.GetScrollOffset(layer_id_, LayerTreeType::PENDING));
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations_impl->Animate(kInitialTickTime + duration);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_VECTOR2DF_EQ(target_value, client_impl_.GetScrollOffset(
+                                        layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(animations_impl->HasActiveAnimation());
+  event = GetMostRecentPropertyUpdateEvent(events.get());
+  EXPECT_FALSE(event);
+
+  animations->Animate(kInitialTickTime + duration);
+  animations->UpdateState(true, nullptr);
+  EXPECT_VECTOR2DF_EQ(
+      target_value, client_.GetScrollOffset(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+TEST_F(ElementAnimationsTest, ScrollOffsetRemovalClearsScrollDelta) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  // First test the 1-argument version of RemoveAnimation.
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+
+  int animation_id = 1;
+  std::unique_ptr<Animation> animation(Animation::Create(
+      std::move(curve), animation_id, 0, TargetProperty::SCROLL_OFFSET));
+  animation->set_needs_synchronized_start_time(true);
+  animations->AddAnimation(std::move(animation));
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  animations->RemoveAnimation(animation_id);
+  EXPECT_TRUE(animations->scroll_offset_animation_was_interrupted());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(animations_impl->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  // Now, test the 2-argument version of RemoveAnimation.
+  curve = ScrollOffsetAnimationCurve::Create(target_value,
+                                             EaseInOutTimingFunction::Create());
+  animation = Animation::Create(std::move(curve), animation_id, 0,
+                                TargetProperty::SCROLL_OFFSET);
+  animation->set_needs_synchronized_start_time(true);
+  animations->AddAnimation(std::move(animation));
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  animations->RemoveAnimation(animation_id);
+  EXPECT_TRUE(animations->scroll_offset_animation_was_interrupted());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(animations_impl->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  // Check that removing non-scroll-offset animations does not cause
+  // scroll_offset_animation_was_interrupted() to get set.
+  animation_id =
+      AddAnimatedTransformToElementAnimations(animations.get(), 1.0, 1, 2);
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  animations->RemoveAnimation(animation_id);
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  animation_id =
+      AddAnimatedFilterToElementAnimations(animations.get(), 1.0, 0.1f, 0.2f);
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+
+  animations->RemoveAnimation(animation_id);
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+  EXPECT_FALSE(animations->scroll_offset_animation_was_interrupted());
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->scroll_offset_animation_was_interrupted());
+}
+
+// Tests that impl-only animations lead to start and finished notifications
+// on the impl thread animations's animation delegate.
+TEST_F(ElementAnimationsTest,
+       NotificationsForImplOnlyAnimationsAreSentToImplThreadDelegate) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  TestAnimationDelegate delegate;
+  player_impl_->set_layer_animation_delegate(&delegate);
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  to_add->set_is_impl_only(true);
+  animations_impl->AddAnimation(std::move(to_add));
+
+  EXPECT_FALSE(delegate.started());
+  EXPECT_FALSE(delegate.finished());
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  EXPECT_TRUE(delegate.started());
+  EXPECT_FALSE(delegate.finished());
+
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+
+  EXPECT_TRUE(delegate.started());
+  EXPECT_TRUE(delegate.finished());
+}
+
+// Tests that specified start times are sent to the main thread delegate
+TEST_F(ElementAnimationsTest, SpecifiedStartTimesAreSentToMainThreadDelegate) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  TestAnimationDelegate delegate;
+  player_->set_layer_animation_delegate(&delegate);
+
+  int animation_id =
+      AddOpacityTransitionToElementAnimations(animations.get(), 1, 0, 1, false);
+
+  const TimeTicks start_time = TicksFromSecondsF(123);
+  animations->GetAnimation(TargetProperty::OPACITY)->set_start_time(start_time);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Synchronize the start times.
+  EXPECT_EQ(1u, events->events_.size());
+  animations->NotifyAnimationStarted(events->events_[0]);
+
+  // Validate start time on the main thread delegate.
+  EXPECT_EQ(start_time, delegate.start_time());
+}
+
+// Tests animations that are waiting for a synchronized start time do not
+// finish.
+TEST_F(ElementAnimationsTest,
+       AnimationsWaitingForStartTimeDoNotFinishIfTheyOutwaitTheirFinish) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  to_add->set_needs_synchronized_start_time(true);
+
+  // We should pause at the first keyframe indefinitely waiting for that
+  // animation to start.
+  animations->AddAnimation(std::move(to_add));
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // Send the synchronized start time.
+  animations->NotifyAnimationStarted(
+      AnimationEvent(AnimationEvent::STARTED, 0, 1, TargetProperty::OPACITY,
+                     kInitialTickTime + TimeDelta::FromMilliseconds(2000)));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(5000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Tests that two queued animations affecting the same property run in sequence.
+TEST_F(ElementAnimationsTest, TrivialQueuing) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 1.f, 0.5f)),
+      2, TargetProperty::OPACITY));
+
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+
+  animations->Animate(kInitialTickTime);
+
+  // The second animation still needs to be started.
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+  animations->UpdateState(true, events.get());
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Tests interrupting a transition with another transition.
+TEST_F(ElementAnimationsTest, Interrupt) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 1.f, 0.5f)),
+      2, TargetProperty::OPACITY));
+  animations->AbortAnimations(TargetProperty::OPACITY);
+  animations->AddAnimation(std::move(to_add));
+
+  // Since the previous animation was aborted, the new animation should start
+  // right in this call to animate.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1500));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Tests scheduling two animations to run together when only one property is
+// free.
+TEST_F(ElementAnimationsTest, ScheduleTogetherWhenAPropertyIsBlocked) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1)), 1,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1)), 2,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      2, TargetProperty::OPACITY));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  // Should not have started the float transition yet.
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  // The float animation should have started at time 1 and should be done.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Tests scheduling two animations to run together with different lengths and
+// another animation queued to start when the shorter animation finishes (should
+// wait for both to finish).
+TEST_F(ElementAnimationsTest, ScheduleTogetherWithAnAnimWaiting) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(2)), 1,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 1.f, 0.5f)),
+      2, TargetProperty::OPACITY));
+
+  // Animations with id 1 should both start now.
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  // The opacity animation should have finished at time 1, but the group
+  // of animations with id 1 don't finish until time 2 because of the length
+  // of the transform animation.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  // Should not have started the float transition yet.
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // The second opacity animation should start at time 2 and should be done by
+  // time 3.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Test that a looping animation loops and for the correct number of iterations.
+TEST_F(ElementAnimationsTest, TrivialLooping) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  to_add->set_iterations(3);
+  animations->AddAnimation(std::move(to_add));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1250));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.25f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1750));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2250));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.25f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2750));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
+  animations->UpdateState(true, events.get());
+  EXPECT_FALSE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // Just be extra sure.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(4000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+// Test that an infinitely looping animation does indeed go until aborted.
+TEST_F(ElementAnimationsTest, InfiniteLooping) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  to_add->set_iterations(-1);
+  animations->AddAnimation(std::move(to_add));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1250));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.25f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1750));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->Animate(kInitialTickTime +
+                      TimeDelta::FromMilliseconds(1073741824250));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.25f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime +
+                      TimeDelta::FromMilliseconds(1073741824750));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_TRUE(animations->GetAnimation(TargetProperty::OPACITY));
+  animations->GetAnimation(TargetProperty::OPACITY)
+      ->SetRunState(Animation::ABORTED,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(750));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+// Test that pausing and resuming work as expected.
+TEST_F(ElementAnimationsTest, PauseResume) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_TRUE(animations->GetAnimation(TargetProperty::OPACITY));
+  animations->GetAnimation(TargetProperty::OPACITY)
+      ->SetRunState(Animation::PAUSED,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(500));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_TRUE(animations->GetAnimation(TargetProperty::OPACITY));
+  animations->GetAnimation(TargetProperty::OPACITY)
+      ->SetRunState(Animation::RUNNING,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(1024000));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024250));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024500));
+  animations->UpdateState(true, events.get());
+  EXPECT_FALSE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, AbortAGroupedAnimation) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int animation_id = 2;
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1)), 1, 1,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(2.0, 0.f, 1.f)),
+      animation_id, 1, TargetProperty::OPACITY));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 1.f, 0.75f)),
+      3, 2, TargetProperty::OPACITY));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.5f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_TRUE(animations->GetAnimationById(animation_id));
+  animations->GetAnimationById(animation_id)
+      ->SetRunState(Animation::ABORTED,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(!animations->HasActiveAnimation());
+  EXPECT_EQ(0.75f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, PushUpdatesWhenSynchronizedStartTimeNeeded) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> to_add(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(2.0, 0.f, 1.f)),
+      0, TargetProperty::OPACITY));
+  to_add->set_needs_synchronized_start_time(true);
+  animations->AddAnimation(std::move(to_add));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  Animation* active_animation =
+      animations->GetAnimation(TargetProperty::OPACITY);
+  EXPECT_TRUE(active_animation);
+  EXPECT_TRUE(active_animation->needs_synchronized_start_time());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+
+  active_animation = animations_impl->GetAnimation(TargetProperty::OPACITY);
+  EXPECT_TRUE(active_animation);
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            active_animation->run_state());
+}
+
+// Tests that skipping a call to UpdateState works as expected.
+TEST_F(ElementAnimationsTest, SkipUpdateState) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  auto events = host_impl_->CreateEvents();
+
+  std::unique_ptr<Animation> first_animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1)), 1,
+      TargetProperty::TRANSFORM));
+  first_animation->set_is_controlling_instance_for_test(true);
+  animations->AddAnimation(std::move(first_animation));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+
+  std::unique_ptr<Animation> second_animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      2, TargetProperty::OPACITY));
+  second_animation->set_is_controlling_instance_for_test(true);
+  animations->AddAnimation(std::move(second_animation));
+
+  // Animate but don't UpdateState.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  events = host_impl_->CreateEvents();
+  animations->UpdateState(true, events.get());
+
+  // Should have one STARTED event and one FINISHED event.
+  EXPECT_EQ(2u, events->events_.size());
+  EXPECT_NE(events->events_[0].type, events->events_[1].type);
+
+  // The float transition should still be at its starting point.
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
+  animations->UpdateState(true, events.get());
+
+  // The float tranisition should now be done.
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(animations->HasActiveAnimation());
+}
+
+// Tests that an animation animations with only a pending observer gets ticked
+// but doesn't progress animations past the STARTING state.
+TEST_F(ElementAnimationsTest, InactiveObserverGetsTicked) {
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int id = 1;
+  animations->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.5f, 1.f)),
+      id, TargetProperty::OPACITY));
+
+  // Without an observer, the animation shouldn't progress to the STARTING
+  // state.
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0u, events->events_.size());
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+
+  // animations->set_needs_pending_value_observations(true);
+  CreateTestImplLayer(LayerTreeType::PENDING);
+
+  // With only a pending observer, the animation should progress to the
+  // STARTING state and get ticked at its starting point, but should not
+  // progress to RUNNING.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0u, events->events_.size());
+  EXPECT_EQ(Animation::STARTING,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+
+  // Even when already in the STARTING state, the animation should stay
+  // there, and shouldn't be ticked past its starting point.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(0u, events->events_.size());
+  EXPECT_EQ(Animation::STARTING,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+
+  // animations->set_needs_active_value_observations(true);
+  CreateTestImplLayer(LayerTreeType::ACTIVE);
+
+  // Now that an active observer has been added, the animation should still
+  // initially tick at its starting point, but should now progress to RUNNING.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
+  animations->UpdateState(true, events.get());
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(Animation::RUNNING,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // The animation should now tick past its starting point.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3500));
+  EXPECT_NE(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_NE(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, TransformAnimationBounds) {
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations1;
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  operations1.AppendTranslate(10.0, 15.0, 0.0);
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations1, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve1), 1, 1, TargetProperty::TRANSFORM));
+  animations_impl->AddAnimation(std::move(animation));
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve2(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations2;
+  curve2->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations2, nullptr));
+  operations2.AppendScale(2.0, 3.0, 4.0);
+  curve2->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve2), 2, 2, TargetProperty::TRANSFORM);
+  animations_impl->AddAnimation(std::move(animation));
+
+  gfx::BoxF box(1.f, 2.f, -1.f, 3.f, 4.f, 5.f);
+  gfx::BoxF bounds;
+
+  EXPECT_TRUE(animations_impl->TransformAnimationBoundsForBox(box, &bounds));
+  EXPECT_EQ(gfx::BoxF(1.f, 2.f, -4.f, 13.f, 19.f, 20.f).ToString(),
+            bounds.ToString());
+
+  animations_impl->GetAnimationById(1)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // Only the unfinished animation should affect the animated bounds.
+  EXPECT_TRUE(animations_impl->TransformAnimationBoundsForBox(box, &bounds));
+  EXPECT_EQ(gfx::BoxF(1.f, 2.f, -4.f, 7.f, 16.f, 20.f).ToString(),
+            bounds.ToString());
+
+  animations_impl->GetAnimationById(2)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // There are no longer any running animations.
+  EXPECT_FALSE(animations_impl->HasTransformAnimationThatInflatesBounds());
+
+  // Add an animation whose bounds we don't yet support computing.
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve3(
+      KeyframedTransformAnimationCurve::Create());
+  TransformOperations operations3;
+  gfx::Transform transform3;
+  transform3.Scale3d(1.0, 2.0, 3.0);
+  curve3->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations3, nullptr));
+  operations3.AppendMatrix(transform3);
+  curve3->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations3, nullptr));
+  animation =
+      Animation::Create(std::move(curve3), 3, 3, TargetProperty::TRANSFORM);
+  animations_impl->AddAnimation(std::move(animation));
+  EXPECT_FALSE(animations_impl->TransformAnimationBoundsForBox(box, &bounds));
+}
+
+// Tests that AbortAnimations aborts all animations targeting the specified
+// property.
+TEST_F(ElementAnimationsTest, AbortAnimations) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  // Start with several animations, and allow some of them to reach the finished
+  // state.
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1.0)), 1, 1,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      2, 2, TargetProperty::OPACITY));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1.0)), 3, 3,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(2.0)), 4, 4,
+      TargetProperty::TRANSFORM));
+  animations->AddAnimation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      5, 5, TargetProperty::OPACITY));
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, nullptr);
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_EQ(Animation::FINISHED, animations->GetAnimationById(1)->run_state());
+  EXPECT_EQ(Animation::FINISHED, animations->GetAnimationById(2)->run_state());
+  EXPECT_EQ(Animation::RUNNING, animations->GetAnimationById(3)->run_state());
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations->GetAnimationById(4)->run_state());
+  EXPECT_EQ(Animation::RUNNING, animations->GetAnimationById(5)->run_state());
+
+  animations->AbortAnimations(TargetProperty::TRANSFORM);
+
+  // Only un-finished TRANSFORM animations should have been aborted.
+  EXPECT_EQ(Animation::FINISHED, animations->GetAnimationById(1)->run_state());
+  EXPECT_EQ(Animation::FINISHED, animations->GetAnimationById(2)->run_state());
+  EXPECT_EQ(Animation::ABORTED, animations->GetAnimationById(3)->run_state());
+  EXPECT_EQ(Animation::ABORTED, animations->GetAnimationById(4)->run_state());
+  EXPECT_EQ(Animation::RUNNING, animations->GetAnimationById(5)->run_state());
+}
+
+// An animation aborted on the main thread should get deleted on both threads.
+TEST_F(ElementAnimationsTest, MainThreadAbortedAnimationGetsDeleted) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  int animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1.0, 0.f, 1.f, false);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+
+  animations->AbortAnimations(TargetProperty::OPACITY);
+  EXPECT_EQ(Animation::ABORTED,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_FALSE(host_->animation_waiting_for_deletion());
+  EXPECT_FALSE(host_impl_->animation_waiting_for_deletion());
+
+  animations->Animate(kInitialTickTime);
+  animations->UpdateState(true, nullptr);
+  EXPECT_FALSE(host_->animation_waiting_for_deletion());
+  EXPECT_EQ(Animation::ABORTED,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_FALSE(animations->GetAnimationById(animation_id));
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id));
+}
+
+// An animation aborted on the impl thread should get deleted on both threads.
+TEST_F(ElementAnimationsTest, ImplThreadAbortedAnimationGetsDeleted) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  TestAnimationDelegate delegate;
+  player_->set_layer_animation_delegate(&delegate);
+
+  int animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1.0, 0.f, 1.f, false);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+
+  animations_impl->AbortAnimations(TargetProperty::OPACITY);
+  EXPECT_EQ(
+      Animation::ABORTED,
+      animations_impl->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_FALSE(host_->animation_waiting_for_deletion());
+  EXPECT_FALSE(host_impl_->animation_waiting_for_deletion());
+
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(host_impl_->animation_waiting_for_deletion());
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::ABORTED, events->events_[0].type);
+  EXPECT_EQ(
+      Animation::WAITING_FOR_DELETION,
+      animations_impl->GetAnimation(TargetProperty::OPACITY)->run_state());
+
+  animations->NotifyAnimationAborted(events->events_[0]);
+  EXPECT_EQ(Animation::ABORTED,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+  EXPECT_TRUE(delegate.aborted());
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(host_->animation_waiting_for_deletion());
+  EXPECT_EQ(Animation::WAITING_FOR_DELETION,
+            animations->GetAnimation(TargetProperty::OPACITY)->run_state());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->GetAnimationById(animation_id));
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id));
+}
+
+// Test that an impl-only scroll offset animation that needs to be completed on
+// the main thread gets deleted.
+TEST_F(ElementAnimationsTest, ImplThreadTakeoverAnimationGetsDeleted) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  TestAnimationDelegate delegate_impl;
+  player_impl_->set_layer_animation_delegate(&delegate_impl);
+  TestAnimationDelegate delegate;
+  player_->set_layer_animation_delegate(&delegate);
+
+  // Add impl-only scroll offset animation.
+  const int animation_id = 1;
+  gfx::ScrollOffset initial_value(100.f, 300.f);
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  std::unique_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(target_value,
+                                         EaseInOutTimingFunction::Create()));
+  curve->SetInitialValue(initial_value);
+  std::unique_ptr<Animation> animation(Animation::Create(
+      std::move(curve), animation_id, 0, TargetProperty::SCROLL_OFFSET));
+  animation->set_start_time(TicksFromSecondsF(123));
+  animation->set_is_impl_only(true);
+  animations_impl->AddAnimation(std::move(animation));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+
+  const bool needs_completion = true;
+  animations_impl->AbortAnimations(TargetProperty::SCROLL_OFFSET,
+                                   needs_completion);
+  EXPECT_EQ(Animation::ABORTED_BUT_NEEDS_COMPLETION,
+            animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET)
+                ->run_state());
+  EXPECT_FALSE(host_->animation_waiting_for_deletion());
+  EXPECT_FALSE(host_impl_->animation_waiting_for_deletion());
+
+  auto events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_TRUE(delegate_impl.finished());
+  EXPECT_TRUE(host_impl_->animation_waiting_for_deletion());
+  EXPECT_EQ(1u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::TAKEOVER, events->events_[0].type);
+  EXPECT_EQ(123, events->events_[0].animation_start_time);
+  EXPECT_EQ(
+      target_value,
+      events->events_[0].curve->ToScrollOffsetAnimationCurve()->target_value());
+  EXPECT_EQ(Animation::WAITING_FOR_DELETION,
+            animations_impl->GetAnimation(TargetProperty::SCROLL_OFFSET)
+                ->run_state());
+
+  animations->NotifyAnimationTakeover(events->events_[0]);
+  EXPECT_TRUE(delegate.takeover());
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations->GetAnimationById(animation_id));
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id));
+}
+
+// Ensure that we only generate FINISHED events for animations in a group
+// once all animations in that group are finished.
+TEST_F(ElementAnimationsTest, FinishedEventsForGroup) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int group_id = 1;
+
+  // Add two animations with the same group id but different durations.
+  std::unique_ptr<Animation> first_animation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(2.0)), 1,
+      group_id, TargetProperty::TRANSFORM));
+  first_animation->set_is_controlling_instance_for_test(true);
+  animations_impl->AddAnimation(std::move(first_animation));
+
+  std::unique_ptr<Animation> second_animation(Animation::Create(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      2, group_id, TargetProperty::OPACITY));
+  second_animation->set_is_controlling_instance_for_test(true);
+  animations_impl->AddAnimation(std::move(second_animation));
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Both animations should have started.
+  EXPECT_EQ(2u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[0].type);
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[1].type);
+
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+
+  // The opacity animation should be finished, but should not have generated
+  // a FINISHED event yet.
+  EXPECT_EQ(0u, events->events_.size());
+  EXPECT_EQ(Animation::FINISHED,
+            animations_impl->GetAnimationById(2)->run_state());
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(1)->run_state());
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(2000));
+  animations_impl->UpdateState(true, events.get());
+
+  // Both animations should have generated FINISHED events.
+  EXPECT_EQ(2u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::FINISHED, events->events_[0].type);
+  EXPECT_EQ(AnimationEvent::FINISHED, events->events_[1].type);
+}
+
+// Ensure that when a group has a mix of aborted and finished animations,
+// we generate a FINISHED event for the finished animation and an ABORTED
+// event for the aborted animation.
+TEST_F(ElementAnimationsTest, FinishedAndAbortedEventsForGroup) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  // Add two animations with the same group id.
+  std::unique_ptr<Animation> first_animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeTransformTransition(1.0)), 1,
+      TargetProperty::TRANSFORM));
+  first_animation->set_is_controlling_instance_for_test(true);
+  animations_impl->AddAnimation(std::move(first_animation));
+
+  std::unique_ptr<Animation> second_animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  second_animation->set_is_controlling_instance_for_test(true);
+  animations_impl->AddAnimation(std::move(second_animation));
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Both animations should have started.
+  EXPECT_EQ(2u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[0].type);
+  EXPECT_EQ(AnimationEvent::STARTED, events->events_[1].type);
+
+  animations_impl->AbortAnimations(TargetProperty::OPACITY);
+
+  events = host_impl_->CreateEvents();
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+
+  // We should have exactly 2 events: a FINISHED event for the tranform
+  // animation, and an ABORTED event for the opacity animation.
+  EXPECT_EQ(2u, events->events_.size());
+  EXPECT_EQ(AnimationEvent::FINISHED, events->events_[0].type);
+  EXPECT_EQ(TargetProperty::TRANSFORM, events->events_[0].target_property);
+  EXPECT_EQ(AnimationEvent::ABORTED, events->events_[1].type);
+  EXPECT_EQ(TargetProperty::OPACITY, events->events_[1].target_property);
+}
+
+TEST_F(ElementAnimationsTest, HasAnimationThatAffectsScale) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_FALSE(animations_impl->HasAnimationThatAffectsScale());
+
+  animations_impl->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+
+  // Opacity animations don't affect scale.
+  EXPECT_FALSE(animations_impl->HasAnimationThatAffectsScale());
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations1;
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  operations1.AppendTranslate(10.0, 15.0, 0.0);
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations1, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve1), 2, 2, TargetProperty::TRANSFORM));
+  animations_impl->AddAnimation(std::move(animation));
+
+  // Translations don't affect scale.
+  EXPECT_FALSE(animations_impl->HasAnimationThatAffectsScale());
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve2(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations2;
+  curve2->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations2, nullptr));
+  operations2.AppendScale(2.0, 3.0, 4.0);
+  curve2->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve2), 3, 3, TargetProperty::TRANSFORM);
+  animations_impl->AddAnimation(std::move(animation));
+
+  EXPECT_TRUE(animations_impl->HasAnimationThatAffectsScale());
+
+  animations_impl->GetAnimationById(3)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // Only unfinished animations should be considered by
+  // HasAnimationThatAffectsScale.
+  EXPECT_FALSE(animations_impl->HasAnimationThatAffectsScale());
+}
+
+TEST_F(ElementAnimationsTest, HasOnlyTranslationTransforms) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+
+  animations_impl->AddAnimation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+
+  // Opacity animations aren't non-translation transforms.
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations1;
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  operations1.AppendTranslate(10.0, 15.0, 0.0);
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations1, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve1), 2, 2, TargetProperty::TRANSFORM));
+  animations_impl->AddAnimation(std::move(animation));
+
+  // The only transform animation we've added is a translation.
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve2(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations2;
+  curve2->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations2, nullptr));
+  operations2.AppendScale(2.0, 3.0, 4.0);
+  curve2->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve2), 3, 3, TargetProperty::TRANSFORM);
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  // A scale animation is not a translation.
+  EXPECT_FALSE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+
+  animations_impl->GetAnimationById(3)->set_affects_pending_observers(false);
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+
+  animations_impl->GetAnimationById(3)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // Only unfinished animations should be considered by
+  // HasOnlyTranslationTransforms.
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations_impl->HasOnlyTranslationTransforms(
+      ElementAnimations::ObserverType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, AnimationStartScale) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations1;
+  operations1.AppendScale(2.0, 3.0, 4.0);
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  TransformOperations operations2;
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve1), 1, 1, TargetProperty::TRANSFORM));
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  float start_scale = 0.f;
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::PENDING, &start_scale));
+  EXPECT_EQ(4.f, start_scale);
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::ACTIVE, &start_scale));
+  EXPECT_EQ(0.f, start_scale);
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::PENDING, &start_scale));
+  EXPECT_EQ(4.f, start_scale);
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::ACTIVE, &start_scale));
+  EXPECT_EQ(4.f, start_scale);
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve2(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations3;
+  curve2->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations3, nullptr));
+  operations3.AppendScale(6.0, 5.0, 4.0);
+  curve2->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations3, nullptr));
+
+  animations_impl->RemoveAnimation(1);
+  animation =
+      Animation::Create(std::move(curve2), 2, 2, TargetProperty::TRANSFORM);
+
+  // Reverse Direction
+  animation->set_direction(Animation::DIRECTION_REVERSE);
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve3(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations4;
+  operations4.AppendScale(5.0, 3.0, 1.0);
+  curve3->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations4, nullptr));
+  TransformOperations operations5;
+  curve3->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations5, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve3), 3, 3, TargetProperty::TRANSFORM);
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::PENDING, &start_scale));
+  EXPECT_EQ(6.f, start_scale);
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::ACTIVE, &start_scale));
+  EXPECT_EQ(0.f, start_scale);
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::PENDING, &start_scale));
+  EXPECT_EQ(6.f, start_scale);
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::ACTIVE, &start_scale));
+  EXPECT_EQ(6.f, start_scale);
+
+  animations_impl->GetAnimationById(2)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // Only unfinished animations should be considered by
+  // AnimationStartScale.
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::PENDING, &start_scale));
+  EXPECT_EQ(5.f, start_scale);
+  EXPECT_TRUE(animations_impl->AnimationStartScale(
+      ElementAnimations::ObserverType::ACTIVE, &start_scale));
+  EXPECT_EQ(5.f, start_scale);
+}
+
+TEST_F(ElementAnimationsTest, MaximumTargetScale) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  float max_scale = 0.f;
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(0.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(0.f, max_scale);
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations1;
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  operations1.AppendScale(2.0, 3.0, 4.0);
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations1, nullptr));
+
+  std::unique_ptr<Animation> animation(
+      Animation::Create(std::move(curve1), 1, 1, TargetProperty::TRANSFORM));
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(0.f, max_scale);
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve2(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations2;
+  curve2->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations2, nullptr));
+  operations2.AppendScale(6.0, 5.0, 4.0);
+  curve2->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve2), 2, 2, TargetProperty::TRANSFORM);
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve3(
+      KeyframedTransformAnimationCurve::Create());
+
+  TransformOperations operations3;
+  curve3->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations3, nullptr));
+  operations3.AppendPerspective(6.0);
+  curve3->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations3, nullptr));
+
+  animation =
+      Animation::Create(std::move(curve3), 3, 3, TargetProperty::TRANSFORM);
+  animation->set_affects_active_observers(false);
+  animations_impl->AddAnimation(std::move(animation));
+
+  EXPECT_FALSE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_FALSE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+
+  animations_impl->GetAnimationById(3)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+  animations_impl->GetAnimationById(2)->SetRunState(Animation::FINISHED,
+                                                    TicksFromSecondsF(0.0));
+
+  // Only unfinished animations should be considered by
+  // MaximumTargetScale.
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(4.f, max_scale);
+}
+
+TEST_F(ElementAnimationsTest, MaximumTargetScaleWithDirection) {
+  CreateTestLayer(true, false);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  std::unique_ptr<KeyframedTransformAnimationCurve> curve1(
+      KeyframedTransformAnimationCurve::Create());
+  TransformOperations operations1;
+  operations1.AppendScale(1.0, 2.0, 3.0);
+  curve1->AddKeyframe(
+      TransformKeyframe::Create(base::TimeDelta(), operations1, nullptr));
+  TransformOperations operations2;
+  operations2.AppendScale(4.0, 5.0, 6.0);
+  curve1->AddKeyframe(TransformKeyframe::Create(
+      base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
+
+  std::unique_ptr<Animation> animation_owned(
+      Animation::Create(std::move(curve1), 1, 1, TargetProperty::TRANSFORM));
+  Animation* animation = animation_owned.get();
+  animations_impl->AddAnimation(std::move(animation_owned));
+
+  float max_scale = 0.f;
+
+  EXPECT_GT(animation->playback_rate(), 0.0);
+
+  // NORMAL direction with positive playback rate.
+  animation->set_direction(Animation::DIRECTION_NORMAL);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+
+  // ALTERNATE direction with positive playback rate.
+  animation->set_direction(Animation::DIRECTION_ALTERNATE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+
+  // REVERSE direction with positive playback rate.
+  animation->set_direction(Animation::DIRECTION_REVERSE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+
+  // ALTERNATE reverse direction.
+  animation->set_direction(Animation::DIRECTION_REVERSE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+
+  animation->set_playback_rate(-1.0);
+
+  // NORMAL direction with negative playback rate.
+  animation->set_direction(Animation::DIRECTION_NORMAL);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+
+  // ALTERNATE direction with negative playback rate.
+  animation->set_direction(Animation::DIRECTION_ALTERNATE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(3.f, max_scale);
+
+  // REVERSE direction with negative playback rate.
+  animation->set_direction(Animation::DIRECTION_REVERSE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+
+  // ALTERNATE reverse direction with negative playback rate.
+  animation->set_direction(Animation::DIRECTION_REVERSE);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::PENDING, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+  EXPECT_TRUE(animations_impl->MaximumTargetScale(
+      ElementAnimations::ObserverType::ACTIVE, &max_scale));
+  EXPECT_EQ(6.f, max_scale);
+}
+
+TEST_F(ElementAnimationsTest, NewlyPushedAnimationWaitsForActivation) {
+  CreateTestLayer(true, true);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  EXPECT_FALSE(animations->needs_to_start_animations_for_testing());
+  int animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1, 0.5f, 1.f, false);
+  EXPECT_TRUE(animations->needs_to_start_animations_for_testing());
+
+  EXPECT_FALSE(animations_impl->needs_to_start_animations_for_testing());
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(animations_impl->needs_to_start_animations_for_testing());
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_pending_observers());
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id)
+                   ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime);
+  EXPECT_FALSE(animations_impl->needs_to_start_animations_for_testing());
+  animations_impl->UpdateState(true, events.get());
+
+  // Since the animation hasn't been activated, it should still be STARTING
+  // rather than RUNNING.
+  EXPECT_EQ(Animation::STARTING,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  // Since the animation hasn't been activated, only the pending observer
+  // should have been ticked.
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+
+  // Since the animation has been activated, it should have reached the
+  // RUNNING state and the active observer should start to get ticked.
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, ActivationBetweenAnimateAndUpdateState) {
+  CreateTestLayer(true, true);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1, 0.5f, 1.f, true);
+
+  animations->PushPropertiesTo(animations_impl.get());
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WAITING_FOR_TARGET_AVAILABILITY,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_pending_observers());
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id)
+                   ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime);
+
+  // Since the animation hasn't been activated, only the pending observer
+  // should have been ticked.
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_active_observers());
+
+  animations_impl->UpdateState(true, events.get());
+
+  // Since the animation has been activated, it should have reached the
+  // RUNNING state.
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+
+  animations_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+
+  // Both observers should have been ticked.
+  EXPECT_EQ(0.75f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.75f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest,
+       ObserverNotifiedWhenTransformIsPotentiallyAnimatingChanges) {
+  CreateTestLayer(true, true);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  EXPECT_FALSE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  // Case 1: An animation that's allowed to run until its finish point.
+  AddAnimatedTransformToElementAnimations(animations.get(), 1.0, 1, 1);
+  EXPECT_TRUE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  animations->NotifyAnimationStarted(events->events_[0]);
+  events->events_.clear();
+
+  // Finish the animation.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  animations->UpdateState(true, nullptr);
+  EXPECT_FALSE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->PushPropertiesTo(animations_impl.get());
+
+  // animations_impl hasn't yet ticked at/past the end of the animation.
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->NotifyAnimationFinished(events->events_[0]);
+  events->events_.clear();
+
+  // Case 2: An animation that's removed before it finishes.
+  int animation_id =
+      AddAnimatedTransformToElementAnimations(animations.get(), 10.0, 2, 2);
+  EXPECT_TRUE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(2000));
+  animations_impl->UpdateState(true, events.get());
+
+  animations->NotifyAnimationStarted(events->events_[0]);
+  events->events_.clear();
+
+  animations->RemoveAnimation(animation_id);
+  EXPECT_FALSE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  // Case 3: An animation that's aborted before it finishes.
+  animation_id =
+      AddAnimatedTransformToElementAnimations(animations.get(), 10.0, 3, 3);
+  EXPECT_TRUE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations->PushPropertiesTo(animations_impl.get());
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_TRUE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(3000));
+  animations_impl->UpdateState(true, events.get());
+
+  animations->NotifyAnimationStarted(events->events_[0]);
+  events->events_.clear();
+
+  animations_impl->AbortAnimations(TargetProperty::TRANSFORM);
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::PENDING));
+  EXPECT_FALSE(
+      client_impl_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(4000));
+  animations_impl->UpdateState(true, events.get());
+
+  animations->NotifyAnimationAborted(events->events_[0]);
+  EXPECT_FALSE(
+      client_.GetTransformIsAnimating(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, ClippedOpacityValues) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  AddOpacityTransitionToElementAnimations(animations.get(), 1, 1.f, 2.f, true);
+
+  animations->Animate(kInitialTickTime);
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // Opacity values are clipped [0,1]
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, ClippedNegativeOpacityValues) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  AddOpacityTransitionToElementAnimations(animations.get(), 1, 0.f, -2.f, true);
+
+  animations->Animate(kInitialTickTime);
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // Opacity values are clipped [0,1]
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, PushedDeletedAnimationWaitsForActivation) {
+  CreateTestLayer(true, true);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1, 0.5f, 1.f, true);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_active_observers());
+
+  // Delete the animation on the main-thread animations.
+  animations->RemoveAnimation(
+      animations->GetAnimation(TargetProperty::OPACITY)->id());
+  animations->PushPropertiesTo(animations_impl.get());
+
+  // The animation should no longer affect pending observers.
+  EXPECT_FALSE(animations_impl->GetAnimationById(animation_id)
+                   ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(animation_id)
+                  ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations_impl->UpdateState(true, events.get());
+
+  // Only the active observer should have been ticked.
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.75f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+
+  // Activation should cause the animation to be deleted.
+  EXPECT_FALSE(animations_impl->has_any_animation());
+}
+
+// Tests that an animation that affects only active observers won't block
+// an animation that affects only pending observers from starting.
+TEST_F(ElementAnimationsTest, StartAnimationsAffectingDifferentObservers) {
+  CreateTestLayer(true, true);
+  AttachTimelinePlayerLayer();
+  CreateImplTimelineAndPlayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+  scoped_refptr<ElementAnimations> animations_impl = element_animations_impl();
+
+  auto events = host_impl_->CreateEvents();
+
+  const int first_animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1, 0.f, 1.f, true);
+
+  animations->PushPropertiesTo(animations_impl.get());
+  animations_impl->ActivateAnimations();
+  animations_impl->Animate(kInitialTickTime);
+  animations_impl->UpdateState(true, events.get());
+
+  // Remove the first animation from the main-thread animations, and add a
+  // new animation affecting the same property.
+  animations->RemoveAnimation(
+      animations->GetAnimation(TargetProperty::OPACITY)->id());
+  const int second_animation_id = AddOpacityTransitionToElementAnimations(
+      animations.get(), 1, 1.f, 0.5f, true);
+  animations->PushPropertiesTo(animations_impl.get());
+
+  // The original animation should only affect active observers, and the new
+  // animation should only affect pending observers.
+  EXPECT_FALSE(animations_impl->GetAnimationById(first_animation_id)
+                   ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(first_animation_id)
+                  ->affects_active_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(second_animation_id)
+                  ->affects_pending_observers());
+  EXPECT_FALSE(animations_impl->GetAnimationById(second_animation_id)
+                   ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  animations_impl->UpdateState(true, events.get());
+
+  // The original animation should still be running, and the new animation
+  // should be starting.
+  EXPECT_EQ(Animation::RUNNING,
+            animations_impl->GetAnimationById(first_animation_id)->run_state());
+  EXPECT_EQ(
+      Animation::STARTING,
+      animations_impl->GetAnimationById(second_animation_id)->run_state());
+
+  // The active observer should have been ticked by the original animation,
+  // and the pending observer should have been ticked by the new animation.
+  EXPECT_EQ(1.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(0.5f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  animations_impl->ActivateAnimations();
+
+  // The original animation should have been deleted, and the new animation
+  // should now affect both observers.
+  EXPECT_FALSE(animations_impl->GetAnimationById(first_animation_id));
+  EXPECT_TRUE(animations_impl->GetAnimationById(second_animation_id)
+                  ->affects_pending_observers());
+  EXPECT_TRUE(animations_impl->GetAnimationById(second_animation_id)
+                  ->affects_active_observers());
+
+  animations_impl->Animate(kInitialTickTime +
+                           TimeDelta::FromMilliseconds(1000));
+  animations_impl->UpdateState(true, events.get());
+
+  // The new animation should be running, and the active observer should have
+  // been ticked at the new animation's starting point.
+  EXPECT_EQ(
+      Animation::RUNNING,
+      animations_impl->GetAnimationById(second_animation_id)->run_state());
+  EXPECT_EQ(1.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::PENDING));
+  EXPECT_EQ(1.f, client_impl_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, TestIsCurrentlyAnimatingProperty) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  // Create an animation that initially affects only pending observers.
+  std::unique_ptr<Animation> animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  animation->set_affects_active_observers(false);
+
+  animations->AddAnimation(std::move(animation));
+  animations->Animate(kInitialTickTime);
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(animations->HasActiveAnimation());
+
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  animations->ActivateAnimations();
+
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(10));
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  EXPECT_EQ(0.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+
+  // Tick past the end of the animation.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1100));
+  animations->UpdateState(true, nullptr);
+
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  EXPECT_EQ(1.f, client_.GetOpacity(layer_id_, LayerTreeType::ACTIVE));
+}
+
+TEST_F(ElementAnimationsTest, TestIsAnimatingPropertyTimeOffsetFillMode) {
+  CreateTestLayer(false, false);
+  AttachTimelinePlayerLayer();
+
+  scoped_refptr<ElementAnimations> animations = element_animations();
+
+  // Create an animation that initially affects only pending observers, and has
+  // a start delay of 2 seconds.
+  std::unique_ptr<Animation> animation(CreateAnimation(
+      std::unique_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)),
+      1, TargetProperty::OPACITY));
+  animation->set_fill_mode(Animation::FILL_MODE_NONE);
+  animation->set_time_offset(TimeDelta::FromMilliseconds(-2000));
+  animation->set_affects_active_observers(false);
+
+  animations->AddAnimation(std::move(animation));
+
+  animations->Animate(kInitialTickTime);
+
+  // Since the animation has a start delay, the observers it affects have a
+  // potentially running transform animation but aren't currently animating
+  // transform.
+  EXPECT_TRUE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  animations->ActivateAnimations();
+
+  EXPECT_TRUE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations->HasActiveAnimation());
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::FILTER, ElementAnimations::ObserverType::ACTIVE));
+
+  animations->UpdateState(true, nullptr);
+
+  // Tick past the start delay.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
+  animations->UpdateState(true, nullptr);
+  EXPECT_TRUE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_TRUE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+
+  // After the animaton finishes, the observers it affects have neither a
+  // potentially running transform animation nor a currently running transform
+  // animation.
+  animations->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(4000));
+  animations->UpdateState(true, nullptr);
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsPotentiallyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::PENDING));
+  EXPECT_FALSE(animations->IsCurrentlyAnimatingProperty(
+      TargetProperty::OPACITY, ElementAnimations::ObserverType::ACTIVE));
+}
+
 }  // namespace
 }  // namespace cc