Update from https://crrev.com/312398

cc/animation/layer_animation_controller_unittest.cc

 // Copyright 2012 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/layer_animation_controller.h"
 
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/animation_registrar.h"
@@ skipping 16 matching lines @@
   return base::TimeTicks::FromInternalValue(seconds *
                                             base::Time::kMicrosecondsPerSecond);
 }
 
 // A LayerAnimationController 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);
 
 scoped_ptr<Animation> CreateAnimation(scoped_ptr<AnimationCurve> curve,
-                                      int id,
+                                      int group_id,
                                       Animation::TargetProperty property) {
-  return Animation::Create(curve.Pass(), 0, id, property);
+  return Animation::Create(curve.Pass(), 0, group_id, property);
 }
 
 TEST(LayerAnimationControllerTest, SyncNewAnimation) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   EXPECT_FALSE(controller_impl->GetAnimation(Animation::Opacity));
 
   EXPECT_FALSE(controller->needs_to_start_animations_for_testing());
   EXPECT_FALSE(controller_impl->needs_to_start_animations_for_testing());
 
-  AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
   EXPECT_TRUE(controller->needs_to_start_animations_for_testing());
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   EXPECT_TRUE(controller_impl->needs_to_start_animations_for_testing());
   controller_impl->ActivateAnimations();
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 }
 
 // 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(LayerAnimationControllerTest, DoNotClobberStartTimes) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   EXPECT_FALSE(controller_impl->GetAnimation(Animation::Opacity));
 
-  AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 
   AnimationEventsVector events;
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, &events);
 
   // Synchronize the start times.
   EXPECT_EQ(1u, events.size());
   controller->NotifyAnimationStarted(events[0]);
-  EXPECT_EQ(controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time(),
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->start_time());
+  EXPECT_EQ(controller->GetAnimationById(animation_id)->start_time(),
+            controller_impl->GetAnimationById(animation_id)->start_time());
 
   // Start the animation on the main thread. Should not affect the start time.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller->UpdateState(true, nullptr);
-  EXPECT_EQ(controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time(),
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->start_time());
+  EXPECT_EQ(controller->GetAnimationById(animation_id)->start_time(),
+            controller_impl->GetAnimationById(animation_id)->start_time());
 }
 
 TEST(LayerAnimationControllerTest, UseSpecifiedStartTimes) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
 
   const TimeTicks start_time = TicksFromSecondsF(123);
   controller->GetAnimation(Animation::Opacity)->set_start_time(start_time);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 
   AnimationEventsVector events;
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, &events);
 
   // Synchronize the start times.
   EXPECT_EQ(1u, events.size());
   controller->NotifyAnimationStarted(events[0]);
 
   EXPECT_EQ(start_time,
-            controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time());
-  EXPECT_EQ(controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time(),
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->start_time());
+            controller->GetAnimationById(animation_id)->start_time());
+  EXPECT_EQ(controller->GetAnimationById(animation_id)->start_time(),
+            controller_impl->GetAnimationById(animation_id)->start_time());
 
   // Start the animation on the main thread. Should not affect the start time.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller->UpdateState(true, nullptr);
   EXPECT_EQ(start_time,
-            controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time());
-  EXPECT_EQ(controller->GetAnimation(group_id,
-                                     Animation::Opacity)->start_time(),
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->start_time());
+            controller->GetAnimationById(animation_id)->start_time());
+  EXPECT_EQ(controller->GetAnimationById(animation_id)->start_time(),
+            controller_impl->GetAnimationById(animation_id)->start_time());
 }
 
 // Tests that controllers activate and deactivate as expected.
 TEST(LayerAnimationControllerTest, Activation) {
   scoped_ptr<AnimationRegistrar> registrar = AnimationRegistrar::Create();
   scoped_ptr<AnimationRegistrar> registrar_impl = AnimationRegistrar::Create();
 
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
@@ skipping 78 matching lines @@
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   EXPECT_FALSE(controller_impl->GetAnimation(Animation::Opacity));
 
-  AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
-  int animation_id = controller->GetAnimation(Animation::Opacity)->id();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 
   // Start the animations on each controller.
   AnimationEventsVector events;
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, &events);
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, nullptr);
   EXPECT_EQ(Animation::Running,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
   EXPECT_EQ(Animation::Running,
-            controller->GetAnimation(group_id,
-                                     Animation::Opacity)->run_state());
+            controller->GetAnimationById(animation_id)->run_state());
 
   // Pause the main-thread animation.
   controller->PauseAnimation(
       animation_id,
       TimeDelta::FromMilliseconds(1000) + TimeDelta::FromMilliseconds(1000));
   EXPECT_EQ(Animation::Paused,
-            controller->GetAnimation(group_id,
-                                     Animation::Opacity)->run_state());
+            controller->GetAnimationById(animation_id)->run_state());
 
   // The pause run state change should make it to the impl thread controller.
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
   EXPECT_EQ(Animation::Paused,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 }
 
 TEST(LayerAnimationControllerTest, DoNotSyncFinishedAnimation) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   EXPECT_FALSE(controller_impl->GetAnimation(Animation::Opacity));
 
   int animation_id =
       AddOpacityTransitionToController(controller.get(), 1, 0, 1, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int group_id = controller->GetAnimationById(animation_id)->group();
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller_impl->GetAnimation(group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(animation_id)->run_state());
 
   // Notify main thread controller that the animation has started.
   AnimationEvent animation_started_event(AnimationEvent::Started,
                                          0,
                                          group_id,
                                          Animation::Opacity,
                                          kInitialTickTime);
   controller->NotifyAnimationStarted(animation_started_event);
 
   // Force animation to complete on impl thread.
   controller_impl->RemoveAnimation(animation_id);
 
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id));
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
   // Even though the main thread has a 'new' animation, it should not be pushed
   // because the animation has already completed on the impl thread.
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id));
 }
 
 // Ensure that a finished animation is eventually deleted by both the
 // main-thread and the impl-thread controllers.
 TEST(LayerAnimationControllerTest, AnimationsAreDeleted) {
   FakeLayerAnimationValueObserver dummy;
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   scoped_refptr<LayerAnimationController> controller(
@@ skipping 487 matching lines @@
   EXPECT_FALSE(event);
 
   controller_impl->Animate(kInitialTickTime + duration);
   controller_impl->UpdateState(true, events.get());
   EXPECT_VECTOR2DF_EQ(target_value, dummy_impl.scroll_offset());
   EXPECT_FALSE(controller_impl->HasActiveAnimation());
   event = GetMostRecentPropertyUpdateEvent(events.get());
   EXPECT_FALSE(event);
 }
 
+TEST(LayerAnimationControllerTest, ScrollOffsetRemovalNotifiesObserver) {
+  FakeLayerAnimationValueObserver dummy;
+  scoped_refptr<LayerAnimationController> controller(
+      LayerAnimationController::Create(0));
+  controller->AddValueObserver(&dummy);
+
+  // First test the 1-argument version of RemoveAnimation.
+  gfx::ScrollOffset target_value(300.f, 200.f);
+  scoped_ptr<ScrollOffsetAnimationCurve> curve(
+      ScrollOffsetAnimationCurve::Create(
+          target_value, EaseInOutTimingFunction::Create().Pass()));
+
+  int animation_id = 1;
+  scoped_ptr<Animation> animation(Animation::Create(
+      curve.Pass(), animation_id, 0, Animation::ScrollOffset));
+  controller->AddAnimation(animation.Pass());
+
+  controller->RemoveAnimation(animation_id);
+  EXPECT_TRUE(dummy.scroll_offset_animation_removed());
+
+  // Now, test the 2-argument version of RemoveAnimation.
+  dummy.reset_scroll_offset_animation_removed();
+  curve = ScrollOffsetAnimationCurve::Create(
+      target_value, EaseInOutTimingFunction::Create().Pass());
+  animation =
+      Animation::Create(curve.Pass(), animation_id, 0, Animation::ScrollOffset);
+  controller->AddAnimation(animation.Pass());
+
+  controller->RemoveAnimation(animation_id, Animation::ScrollOffset);
+  EXPECT_TRUE(dummy.scroll_offset_animation_removed());
+
+  // Check that removing non-scroll-offset animations does not cause the
+  // observer to get notified.
+  dummy.reset_scroll_offset_animation_removed();
+  animation_id = AddAnimatedTransformToController(controller.get(), 1.0, 1, 2);
+  controller->RemoveAnimation(animation_id);
+  EXPECT_FALSE(dummy.scroll_offset_animation_removed());
+
+  dummy.reset_scroll_offset_animation_removed();
+  animation_id =
+      AddAnimatedFilterToController(controller.get(), 1.0, 0.1f, 0.2f);
+  controller->RemoveAnimation(animation_id, Animation::Filter);
+  EXPECT_FALSE(dummy.scroll_offset_animation_removed());
+}
+
 class FakeAnimationDelegate : public AnimationDelegate {
  public:
   FakeAnimationDelegate()
       : started_(false),
         finished_(false) {}
 
   void NotifyAnimationStarted(TimeTicks monotonic_time,
                               Animation::TargetProperty target_property,
                               int group) override {
     started_ = true;
@@ skipping 315 matching lines @@
 
 // Test that an infinitely looping animation does indeed go until aborted.
 TEST(LayerAnimationControllerTest, InfiniteLooping) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  const int id = 1;
   scoped_ptr<Animation> to_add(CreateAnimation(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)).Pass(),
-      id,
-      Animation::Opacity));
+      1, Animation::Opacity));
   to_add->set_iterations(-1);
   controller->AddAnimation(to_add.Pass());
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.f, dummy.opacity());
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1250));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.25f, dummy.opacity());
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1750));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.75f, dummy.opacity());
 
   controller->Animate(kInitialTickTime +
                       TimeDelta::FromMilliseconds(1073741824250));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.25f, dummy.opacity());
   controller->Animate(kInitialTickTime +
                       TimeDelta::FromMilliseconds(1073741824750));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.75f, dummy.opacity());
 
-  EXPECT_TRUE(controller->GetAnimation(id, Animation::Opacity));
-  controller->GetAnimation(id, Animation::Opacity)->SetRunState(
-      Animation::Aborted, kInitialTickTime + TimeDelta::FromMilliseconds(750));
+  EXPECT_TRUE(controller->GetAnimation(Animation::Opacity));
+  controller->GetAnimation(Animation::Opacity)
+      ->SetRunState(Animation::Aborted,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(750));
   EXPECT_FALSE(controller->HasActiveAnimation());
   EXPECT_EQ(0.75f, dummy.opacity());
 }
 
 // Test that pausing and resuming work as expected.
 TEST(LayerAnimationControllerTest, PauseResume) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  const int id = 1;
   controller->AddAnimation(CreateAnimation(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)).Pass(),
-      id,
-      Animation::Opacity));
+      1, Animation::Opacity));
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.f, dummy.opacity());
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.5f, dummy.opacity());
 
-  EXPECT_TRUE(controller->GetAnimation(id, Animation::Opacity));
-  controller->GetAnimation(id, Animation::Opacity)->SetRunState(
-      Animation::Paused, kInitialTickTime + TimeDelta::FromMilliseconds(500));
+  EXPECT_TRUE(controller->GetAnimation(Animation::Opacity));
+  controller->GetAnimation(Animation::Opacity)
+      ->SetRunState(Animation::Paused,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(500));
 
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024000));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.5f, dummy.opacity());
 
-  EXPECT_TRUE(controller->GetAnimation(id, Animation::Opacity));
-  controller->GetAnimation(id, Animation::Opacity)
+  EXPECT_TRUE(controller->GetAnimation(Animation::Opacity));
+  controller->GetAnimation(Animation::Opacity)
       ->SetRunState(Animation::Running,
                     kInitialTickTime + TimeDelta::FromMilliseconds(1024000));
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024250));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.75f, dummy.opacity());
 
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1024500));
   controller->UpdateState(true, events.get());
   EXPECT_FALSE(controller->HasActiveAnimation());
   EXPECT_EQ(1.f, dummy.opacity());
 }
 
 TEST(LayerAnimationControllerTest, AbortAGroupedAnimation) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  const int id = 1;
-  controller->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1)).Pass(),
-      id,
+  const int animation_id = 2;
+  controller->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1)).Pass(), 1, 1,
       Animation::Transform));
-  controller->AddAnimation(CreateAnimation(
+  controller->AddAnimation(Animation::Create(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(2.0, 0.f, 1.f)).Pass(),
-      id,
-      Animation::Opacity));
-  controller->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(
-          new FakeFloatTransition(1.0, 1.f, 0.75f)).Pass(),
-      2,
-      Animation::Opacity));
+      animation_id, 1, Animation::Opacity));
+  controller->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 1.f, 0.75f))
+          .Pass(),
+      3, 2, Animation::Opacity));
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.f, dummy.opacity());
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(0.5f, dummy.opacity());
 
-  EXPECT_TRUE(controller->GetAnimation(id, Animation::Opacity));
-  controller->GetAnimation(id, Animation::Opacity)->SetRunState(
-      Animation::Aborted, kInitialTickTime + TimeDelta::FromMilliseconds(1000));
+  EXPECT_TRUE(controller->GetAnimationById(animation_id));
+  controller->GetAnimationById(animation_id)
+      ->SetRunState(Animation::Aborted,
+                    kInitialTickTime + TimeDelta::FromMilliseconds(1000));
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
   EXPECT_EQ(1.f, dummy.opacity());
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(!controller->HasActiveAnimation());
   EXPECT_EQ(0.75f, dummy.opacity());
 }
 
@@ skipping 12 matching lines @@
   scoped_ptr<Animation> to_add(CreateAnimation(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(2.0, 0.f, 1.f)).Pass(),
       0,
       Animation::Opacity));
   to_add->set_needs_synchronized_start_time(true);
   controller->AddAnimation(to_add.Pass());
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, events.get());
   EXPECT_TRUE(controller->HasActiveAnimation());
-  Animation* active_animation = controller->GetAnimation(0, Animation::Opacity);
+  Animation* active_animation = controller->GetAnimation(Animation::Opacity);
   EXPECT_TRUE(active_animation);
   EXPECT_TRUE(active_animation->needs_synchronized_start_time());
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
 
-  active_animation = controller_impl->GetAnimation(0, Animation::Opacity);
+  active_animation = controller_impl->GetAnimation(Animation::Opacity);
   EXPECT_TRUE(active_animation);
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
             active_animation->run_state());
 }
 
 // Tests that skipping a call to UpdateState works as expected.
 TEST(LayerAnimationControllerTest, SkipUpdateState) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy;
@@ skipping 52 matching lines @@
       new FakeFloatTransition(1.0, 0.5f, 1.f)).Pass(),
       id,
       Animation::Opacity));
 
   // Without an observer, the animation shouldn't progress to the Starting
   // state.
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, events.get());
   EXPECT_EQ(0u, events->size());
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller->GetAnimation(id, Animation::Opacity)->run_state());
+            controller->GetAnimation(Animation::Opacity)->run_state());
 
   controller->AddValueObserver(&pending_dummy);
 
   // 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.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
   controller->UpdateState(true, events.get());
   EXPECT_EQ(0u, events->size());
   EXPECT_EQ(Animation::Starting,
-            controller->GetAnimation(id, Animation::Opacity)->run_state());
+            controller->GetAnimation(Animation::Opacity)->run_state());
   EXPECT_EQ(0.5f, pending_dummy.opacity());
 
   // Even when already in the Starting state, the animation should stay
   // there, and shouldn't be ticked past its starting point.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
   controller->UpdateState(true, events.get());
   EXPECT_EQ(0u, events->size());
   EXPECT_EQ(Animation::Starting,
-            controller->GetAnimation(id, Animation::Opacity)->run_state());
+            controller->GetAnimation(Animation::Opacity)->run_state());
   EXPECT_EQ(0.5f, pending_dummy.opacity());
 
   controller->AddValueObserver(&dummy);
 
   // Now that an active observer has been added, the animation should still
   // initially tick at its starting point, but should now progress to Running.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3000));
   controller->UpdateState(true, events.get());
   EXPECT_EQ(1u, events->size());
   EXPECT_EQ(Animation::Running,
-            controller->GetAnimation(id, Animation::Opacity)->run_state());
+            controller->GetAnimation(Animation::Opacity)->run_state());
   EXPECT_EQ(0.5f, pending_dummy.opacity());
   EXPECT_EQ(0.5f, dummy.opacity());
 
   // The animation should now tick past its starting point.
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(3500));
   EXPECT_NE(0.5f, pending_dummy.opacity());
   EXPECT_NE(0.5f, dummy.opacity());
 }
 
 TEST(LayerAnimationControllerTest, TransformAnimationBounds) {
@@ skipping 27 matching lines @@
   animation = Animation::Create(curve2.Pass(), 2, 2, Animation::Transform);
   controller_impl->AddAnimation(animation.Pass());
 
   gfx::BoxF box(1.f, 2.f, -1.f, 3.f, 4.f, 5.f);
   gfx::BoxF bounds;
 
   EXPECT_TRUE(controller_impl->TransformAnimationBoundsForBox(box, &bounds));
   EXPECT_EQ(gfx::BoxF(1.f, 2.f, -4.f, 13.f, 19.f, 20.f).ToString(),
             bounds.ToString());
 
-  controller_impl->GetAnimation(1, Animation::Transform)
+  controller_impl->GetAnimationById(1)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
 
   // Only the unfinished animation should affect the animated bounds.
   EXPECT_TRUE(controller_impl->TransformAnimationBoundsForBox(box, &bounds));
   EXPECT_EQ(gfx::BoxF(1.f, 2.f, -4.f, 7.f, 16.f, 20.f).ToString(),
             bounds.ToString());
 
-  controller_impl->GetAnimation(2, Animation::Transform)
+  controller_impl->GetAnimationById(2)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
 
   // There are no longer any running animations.
   EXPECT_FALSE(controller_impl->HasTransformAnimationThatInflatesBounds());
 
   // Add an animation whose bounds we don't yet support computing.
   scoped_ptr<KeyframedTransformAnimationCurve> curve3(
       KeyframedTransformAnimationCurve::Create());
   TransformOperations operations3;
   gfx::Transform transform3;
@@ skipping 11 matching lines @@
 // Tests that AbortAnimations aborts all animations targeting the specified
 // property.
 TEST(LayerAnimationControllerTest, AbortAnimations) {
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   // Start with several animations, and allow some of them to reach the finished
   // state.
-  controller->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1.0)).Pass(),
-      1,
+  controller->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1.0)).Pass(), 1, 1,
       Animation::Transform));
-  controller->AddAnimation(CreateAnimation(
+  controller->AddAnimation(Animation::Create(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)).Pass(),
-      2,
-      Animation::Opacity));
-  controller->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1.0)).Pass(),
-      3,
+      2, 2, Animation::Opacity));
+  controller->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeTransformTransition(1.0)).Pass(), 3, 3,
       Animation::Transform));
-  controller->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(new FakeTransformTransition(2.0)).Pass(),
-      4,
+  controller->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeTransformTransition(2.0)).Pass(), 4, 4,
       Animation::Transform));
-  controller->AddAnimation(CreateAnimation(
+  controller->AddAnimation(Animation::Create(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)).Pass(),
-      5,
-      Animation::Opacity));
+      5, 5, Animation::Opacity));
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, nullptr);
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(1000));
   controller->UpdateState(true, nullptr);
 
-  EXPECT_EQ(Animation::Finished,
-            controller->GetAnimation(1, Animation::Transform)->run_state());
-  EXPECT_EQ(Animation::Finished,
-            controller->GetAnimation(2, Animation::Opacity)->run_state());
-  EXPECT_EQ(Animation::Running,
-            controller->GetAnimation(3, Animation::Transform)->run_state());
+  EXPECT_EQ(Animation::Finished, controller->GetAnimationById(1)->run_state());
+  EXPECT_EQ(Animation::Finished, controller->GetAnimationById(2)->run_state());
+  EXPECT_EQ(Animation::Running, controller->GetAnimationById(3)->run_state());
   EXPECT_EQ(Animation::WaitingForTargetAvailability,
-            controller->GetAnimation(4, Animation::Transform)->run_state());
-  EXPECT_EQ(Animation::Running,
-            controller->GetAnimation(5, Animation::Opacity)->run_state());
+            controller->GetAnimationById(4)->run_state());
+  EXPECT_EQ(Animation::Running, controller->GetAnimationById(5)->run_state());
 
   controller->AbortAnimations(Animation::Transform);
 
   // Only un-finished Transform animations should have been aborted.
-  EXPECT_EQ(Animation::Finished,
-            controller->GetAnimation(1, Animation::Transform)->run_state());
-  EXPECT_EQ(Animation::Finished,
-            controller->GetAnimation(2, Animation::Opacity)->run_state());
-  EXPECT_EQ(Animation::Aborted,
-            controller->GetAnimation(3, Animation::Transform)->run_state());
-  EXPECT_EQ(Animation::Aborted,
-            controller->GetAnimation(4, Animation::Transform)->run_state());
-  EXPECT_EQ(Animation::Running,
-            controller->GetAnimation(5, Animation::Opacity)->run_state());
+  EXPECT_EQ(Animation::Finished, controller->GetAnimationById(1)->run_state());
+  EXPECT_EQ(Animation::Finished, controller->GetAnimationById(2)->run_state());
+  EXPECT_EQ(Animation::Aborted, controller->GetAnimationById(3)->run_state());
+  EXPECT_EQ(Animation::Aborted, controller->GetAnimationById(4)->run_state());
+  EXPECT_EQ(Animation::Running, controller->GetAnimationById(5)->run_state());
 }
 
 // An animation aborted on the main thread should get deleted on both threads.
 TEST(LayerAnimationControllerTest, MainThreadAbortedAnimationGetsDeleted) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1.0, 0.f, 1.f, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1.0, 0.f, 1.f, false);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
 
   controller->AbortAnimations(Animation::Opacity);
   EXPECT_EQ(Animation::Aborted,
             controller->GetAnimation(Animation::Opacity)->run_state());
   EXPECT_FALSE(dummy.animation_waiting_for_deletion());
   EXPECT_FALSE(dummy_impl.animation_waiting_for_deletion());
 
   controller->Animate(kInitialTickTime);
   controller->UpdateState(true, nullptr);
   EXPECT_TRUE(dummy.animation_waiting_for_deletion());
   EXPECT_EQ(Animation::WaitingForDeletion,
             controller->GetAnimation(Animation::Opacity)->run_state());
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
-  EXPECT_FALSE(controller->GetAnimation(group_id, Animation::Opacity));
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_FALSE(controller->GetAnimationById(animation_id));
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id));
 }
 
 // An animation aborted on the impl thread should get deleted on both threads.
 TEST(LayerAnimationControllerTest, ImplThreadAbortedAnimationGetsDeleted) {
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1.0, 0.f, 1.f, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1.0, 0.f, 1.f, false);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
 
   controller_impl->AbortAnimations(Animation::Opacity);
   EXPECT_EQ(Animation::Aborted,
             controller_impl->GetAnimation(Animation::Opacity)->run_state());
   EXPECT_FALSE(dummy.animation_waiting_for_deletion());
   EXPECT_FALSE(dummy_impl.animation_waiting_for_deletion());
 
   AnimationEventsVector events;
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, &events);
   EXPECT_TRUE(dummy_impl.animation_waiting_for_deletion());
   EXPECT_EQ(1u, events.size());
   EXPECT_EQ(AnimationEvent::Aborted, events[0].type);
   EXPECT_EQ(Animation::WaitingForDeletion,
             controller_impl->GetAnimation(Animation::Opacity)->run_state());
 
   controller->NotifyAnimationAborted(events[0]);
   EXPECT_EQ(Animation::Aborted,
             controller->GetAnimation(Animation::Opacity)->run_state());
 
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller->UpdateState(true, nullptr);
   EXPECT_TRUE(dummy.animation_waiting_for_deletion());
   EXPECT_EQ(Animation::WaitingForDeletion,
             controller->GetAnimation(Animation::Opacity)->run_state());
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
-  EXPECT_FALSE(controller->GetAnimation(group_id, Animation::Opacity));
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity));
+  EXPECT_FALSE(controller->GetAnimationById(animation_id));
+  EXPECT_FALSE(controller_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(LayerAnimationControllerTest, FinishedEventsForGroup) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
 
+  const int group_id = 1;
+
   // Add two animations with the same group id but different durations.
-  controller_impl->AddAnimation(CreateAnimation(
-      scoped_ptr<AnimationCurve>(new FakeTransformTransition(2.0)).Pass(),
-      1,
-      Animation::Transform));
-  controller_impl->AddAnimation(CreateAnimation(
+  controller_impl->AddAnimation(Animation::Create(
+      scoped_ptr<AnimationCurve>(new FakeTransformTransition(2.0)).Pass(), 1,
+      group_id, Animation::Transform));
+  controller_impl->AddAnimation(Animation::Create(
       scoped_ptr<AnimationCurve>(new FakeFloatTransition(1.0, 0.f, 1.f)).Pass(),
-      1,
-      Animation::Opacity));
+      2, group_id, Animation::Opacity));
 
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, events.get());
 
   // Both animations should have started.
   EXPECT_EQ(2u, events->size());
   EXPECT_EQ(AnimationEvent::Started, (*events)[0].type);
   EXPECT_EQ(AnimationEvent::Started, (*events)[1].type);
 
   events.reset(new AnimationEventsVector);
   controller_impl->Animate(kInitialTickTime +
                            TimeDelta::FromMilliseconds(1000));
   controller_impl->UpdateState(true, events.get());
 
   // The opacity animation should be finished, but should not have generated
   // a Finished event yet.
   EXPECT_EQ(0u, events->size());
   EXPECT_EQ(Animation::Finished,
-            controller_impl->GetAnimation(1, Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(2)->run_state());
   EXPECT_EQ(Animation::Running,
-            controller_impl->GetAnimation(1,
-                                          Animation::Transform)->run_state());
+            controller_impl->GetAnimationById(1)->run_state());
 
   controller_impl->Animate(kInitialTickTime +
                            TimeDelta::FromMilliseconds(2000));
   controller_impl->UpdateState(true, events.get());
 
   // Both animations should have generated Finished events.
   EXPECT_EQ(2u, events->size());
   EXPECT_EQ(AnimationEvent::Finished, (*events)[0].type);
   EXPECT_EQ(AnimationEvent::Finished, (*events)[1].type);
 }
@@ skipping 82 matching lines @@
       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(curve2.Pass(), 3, 3, Animation::Transform);
   controller_impl->AddAnimation(animation.Pass());
 
   EXPECT_TRUE(controller_impl->HasAnimationThatAffectsScale());
 
-  controller_impl->GetAnimation(3, Animation::Transform)
+  controller_impl->GetAnimationById(3)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
 
   // Only unfinished animations should be considered by
   // HasAnimationThatAffectsScale.
   EXPECT_FALSE(controller_impl->HasAnimationThatAffectsScale());
 }
 
 TEST(LayerAnimationControllerTest, HasOnlyTranslationTransforms) {
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
@@ skipping 34 matching lines @@
   operations2.AppendScale(2.0, 3.0, 4.0);
   curve2->AddKeyframe(TransformKeyframe::Create(
       base::TimeDelta::FromSecondsD(1.0), operations2, nullptr));
 
   animation = Animation::Create(curve2.Pass(), 3, 3, Animation::Transform);
   controller_impl->AddAnimation(animation.Pass());
 
   // A scale animation is not a translation.
   EXPECT_FALSE(controller_impl->HasOnlyTranslationTransforms());
 
-  controller_impl->GetAnimation(3, Animation::Transform)
+  controller_impl->GetAnimationById(3)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
 
   // Only unfinished animations should be considered by
   // HasOnlyTranslationTransforms.
   EXPECT_TRUE(controller_impl->HasOnlyTranslationTransforms());
 }
 
 TEST(LayerAnimationControllerTest, MaximumTargetScale) {
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
@@ skipping 43 matching lines @@
       TransformKeyframe::Create(base::TimeDelta(), operations3, nullptr));
   operations3.AppendPerspective(6.0);
   curve3->AddKeyframe(TransformKeyframe::Create(
       base::TimeDelta::FromSecondsD(1.0), operations3, nullptr));
 
   animation = Animation::Create(curve3.Pass(), 3, 3, Animation::Transform);
   controller_impl->AddAnimation(animation.Pass());
 
   EXPECT_FALSE(controller_impl->MaximumTargetScale(&max_scale));
 
-  controller_impl->GetAnimation(3, Animation::Transform)
+  controller_impl->GetAnimationById(3)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
-  controller_impl->GetAnimation(2, Animation::Transform)
+  controller_impl->GetAnimationById(2)
       ->SetRunState(Animation::Finished, TicksFromSecondsF(0.0));
 
   // Only unfinished animations should be considered by
   // MaximumTargetScale.
   EXPECT_TRUE(controller_impl->MaximumTargetScale(&max_scale));
   EXPECT_EQ(4.f, max_scale);
 }
 
 TEST(LayerAnimationControllerTest, MaximumTargetScaleWithDirection) {
   scoped_refptr<LayerAnimationController> controller_impl(
@@ skipping 70 matching lines @@
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   controller_impl->AddValueObserver(&pending_dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
   EXPECT_FALSE(controller->needs_to_start_animations_for_testing());
-  AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, false);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, false);
   EXPECT_TRUE(controller->needs_to_start_animations_for_testing());
 
   EXPECT_FALSE(controller_impl->needs_to_start_animations_for_testing());
   controller->PushAnimationUpdatesTo(controller_impl.get());
   EXPECT_TRUE(controller_impl->needs_to_start_animations_for_testing());
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
-  EXPECT_EQ(
-      Animation::WaitingForTargetAvailability,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WaitingForTargetAvailability,
+            controller_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_pending_observers());
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id)
                    ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime);
   EXPECT_FALSE(controller_impl->needs_to_start_animations_for_testing());
   controller_impl->UpdateState(true, events.get());
 
   // Since the animation hasn't been activated, it should still be Starting
   // rather than Running.
-  EXPECT_EQ(
-      Animation::Starting,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
+  EXPECT_EQ(Animation::Starting,
+            controller_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, pending_dummy_impl.opacity());
   EXPECT_EQ(0.f, dummy_impl.opacity());
 
   controller_impl->ActivateAnimations();
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime +
                            TimeDelta::FromMilliseconds(1000));
   controller_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,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
+  EXPECT_EQ(Animation::Running,
+            controller_impl->GetAnimationById(animation_id)->run_state());
   EXPECT_EQ(0.5f, pending_dummy_impl.opacity());
   EXPECT_EQ(0.5f, dummy_impl.opacity());
 }
 
 TEST(LayerAnimationControllerTest, ActivationBetweenAnimateAndUpdateState) {
   scoped_ptr<AnimationEventsVector> events(
       make_scoped_ptr(new AnimationEventsVector));
   FakeLayerAnimationValueObserver dummy_impl;
   FakeInactiveLayerAnimationValueObserver pending_dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   controller_impl->AddValueObserver(&pending_dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, true);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, true);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity));
-  EXPECT_EQ(
-      Animation::WaitingForTargetAvailability,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id));
+  EXPECT_EQ(Animation::WaitingForTargetAvailability,
+            controller_impl->GetAnimationById(animation_id)->run_state());
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_pending_observers());
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id)
                    ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime);
 
   // Since the animation hasn't been activated, only the pending observer
   // should have been ticked.
   EXPECT_EQ(0.5f, pending_dummy_impl.opacity());
   EXPECT_EQ(0.f, dummy_impl.opacity());
 
   controller_impl->ActivateAnimations();
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_active_observers());
 
   controller_impl->UpdateState(true, events.get());
 
   // Since the animation has been activated, it should have reached the
   // Running state.
-  EXPECT_EQ(
-      Animation::Running,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
+  EXPECT_EQ(Animation::Running,
+            controller_impl->GetAnimationById(animation_id)->run_state());
 
   controller_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
 
   // Both observers should have been ticked.
   EXPECT_EQ(0.75f, pending_dummy_impl.opacity());
   EXPECT_EQ(0.75f, dummy_impl.opacity());
 }
 
 TEST(LayerAnimationControllerTest, ClippedOpacityValues) {
   FakeLayerAnimationValueObserver dummy;
@@ skipping 34 matching lines @@
   FakeInactiveLayerAnimationValueObserver pending_dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   controller_impl->AddValueObserver(&pending_dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, true);
-  int group_id = controller->GetAnimation(Animation::Opacity)->group();
+  int animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0.5f, 1.f, true);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, events.get());
-  EXPECT_EQ(
-      Animation::Running,
-      controller_impl->GetAnimation(group_id, Animation::Opacity)->run_state());
+  EXPECT_EQ(Animation::Running,
+            controller_impl->GetAnimationById(animation_id)->run_state());
   EXPECT_EQ(0.5f, pending_dummy_impl.opacity());
   EXPECT_EQ(0.5f, dummy_impl.opacity());
 
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_active_observers());
 
   // Delete the animation on the main-thread controller.
   controller->RemoveAnimation(
       controller->GetAnimation(Animation::Opacity)->id());
   controller->PushAnimationUpdatesTo(controller_impl.get());
 
   // The animation should no longer affect pending observers.
-  EXPECT_FALSE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(animation_id)
                    ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(group_id, Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(animation_id)
                   ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller_impl->UpdateState(true, events.get());
 
   // Only the active observer should have been ticked.
   EXPECT_EQ(0.5f, pending_dummy_impl.opacity());
   EXPECT_EQ(0.75f, dummy_impl.opacity());
 
   controller_impl->ActivateAnimations();
@@ skipping 11 matching lines @@
   FakeInactiveLayerAnimationValueObserver pending_dummy_impl;
   scoped_refptr<LayerAnimationController> controller_impl(
       LayerAnimationController::Create(0));
   controller_impl->AddValueObserver(&dummy_impl);
   controller_impl->AddValueObserver(&pending_dummy_impl);
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
-  AddOpacityTransitionToController(controller.get(), 1, 0.f, 1.f, true);
-  int first_animation_group_id =
-      controller->GetAnimation(Animation::Opacity)->group();
+  int first_animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 0.f, 1.f, true);
 
   controller->PushAnimationUpdatesTo(controller_impl.get());
   controller_impl->ActivateAnimations();
   controller_impl->Animate(kInitialTickTime);
   controller_impl->UpdateState(true, events.get());
 
   // Remove the first animation from the main-thread controller, and add a
   // new animation affecting the same property.
   controller->RemoveAnimation(
       controller->GetAnimation(Animation::Opacity)->id());
-  AddOpacityTransitionToController(controller.get(), 1, 1.f, 0.5f, true);
-  int second_animation_group_id =
-      controller->GetAnimation(Animation::Opacity)->group();
+  int second_animation_id =
+      AddOpacityTransitionToController(controller.get(), 1, 1.f, 0.5f, true);
   controller->PushAnimationUpdatesTo(controller_impl.get());
 
   // The original animation should only affect active observers, and the new
   // animation should only affect pending observers.
-  EXPECT_FALSE(controller_impl->GetAnimation(first_animation_group_id,
-                                             Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(first_animation_id)
                    ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(first_animation_group_id,
-                                            Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(first_animation_id)
                   ->affects_active_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(second_animation_group_id,
-                                            Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(second_animation_id)
                   ->affects_pending_observers());
-  EXPECT_FALSE(controller_impl->GetAnimation(second_animation_group_id,
-                                             Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(second_animation_id)
                    ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(500));
   controller_impl->UpdateState(true, events.get());
 
   // The original animation should still be running, and the new animation
   // should be starting.
   EXPECT_EQ(Animation::Running,
-            controller_impl->GetAnimation(first_animation_group_id,
-                                          Animation::Opacity)->run_state());
-  EXPECT_EQ(Animation::Starting,
-            controller_impl->GetAnimation(second_animation_group_id,
-                                          Animation::Opacity)->run_state());
+            controller_impl->GetAnimationById(first_animation_id)->run_state());
+  EXPECT_EQ(
+      Animation::Starting,
+      controller_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, pending_dummy_impl.opacity());
   EXPECT_EQ(0.5f, dummy_impl.opacity());
 
   controller_impl->ActivateAnimations();
 
   // The original animation should have been deleted, and the new animation
   // should now affect both observers.
-  EXPECT_FALSE(controller_impl->GetAnimation(first_animation_group_id,
-                                             Animation::Opacity));
-  EXPECT_TRUE(controller_impl->GetAnimation(second_animation_group_id,
-                                            Animation::Opacity)
+  EXPECT_FALSE(controller_impl->GetAnimationById(first_animation_id));
+  EXPECT_TRUE(controller_impl->GetAnimationById(second_animation_id)
                   ->affects_pending_observers());
-  EXPECT_TRUE(controller_impl->GetAnimation(second_animation_group_id,
-                                            Animation::Opacity)
+  EXPECT_TRUE(controller_impl->GetAnimationById(second_animation_id)
                   ->affects_active_observers());
 
   controller_impl->Animate(kInitialTickTime +
                            TimeDelta::FromMilliseconds(1000));
   controller_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,
-            controller_impl->GetAnimation(second_animation_group_id,
-                                          Animation::Opacity)->run_state());
+  EXPECT_EQ(
+      Animation::Running,
+      controller_impl->GetAnimationById(second_animation_id)->run_state());
   EXPECT_EQ(1.f, pending_dummy_impl.opacity());
   EXPECT_EQ(1.f, dummy_impl.opacity());
 }
 
 TEST(LayerAnimationControllerTest, TestIsAnimatingProperty) {
   FakeLayerAnimationValueObserver dummy;
   scoped_refptr<LayerAnimationController> controller(
       LayerAnimationController::Create(0));
   controller->AddValueObserver(&dummy);
 
@@ skipping 32 matching lines @@
   EXPECT_FALSE(controller->IsAnimatingProperty(Animation::Opacity));
   EXPECT_FALSE(controller->IsAnimatingProperty(Animation::Filter));
 
   controller->Animate(kInitialTickTime + TimeDelta::FromMilliseconds(2000));
   controller->UpdateState(true, nullptr);
   EXPECT_TRUE(controller->IsAnimatingProperty(Animation::Opacity));
 }
 
 }  // namespace
 }  // namespace cc