Fixing race conditions in ui::content::WindowSlider which could cause the overscroll overlay to nev…

content/browser/web_contents/aura/window_slider_unittest.cc

Index: content/browser/web_contents/aura/window_slider_unittest.cc
diff --git a/content/browser/web_contents/aura/window_slider_unittest.cc b/content/browser/web_contents/aura/window_slider_unittest.cc
index ed41347ee4d659bdbb81ef0c3a1a4a79b0d786fb..6582186ad9edaad6a62120bf57f5deb83aff1c47 100644
--- a/content/browser/web_contents/aura/window_slider_unittest.cc
+++ b/content/browser/web_contents/aura/window_slider_unittest.cc
@@ -5,13 +5,21 @@
 #include "content/browser/web_contents/aura/window_slider.h"
 
 #include "base/bind.h"
+#include "base/time/time.h"
+#include "cc/animation/animation.h"
+#include "cc/animation/animation_events.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/aura/test/aura_test_base.h"
 #include "ui/aura/test/event_generator.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/window.h"
 #include "ui/base/hit_test.h"
+#include "ui/compositor/layer_animation_sequence.h"
+#include "ui/compositor/scoped_animation_duration_scale_mode.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/compositor/test/layer_animator_test_controller.h"
 #include "ui/events/event_processor.h"
+#include "ui/events/event_utils.h"
 
 namespace content {
 
@@ -39,6 +47,28 @@ void ChangeSliderOwnerDuringScrollCallback(scoped_ptr<aura::Window>* window,
   window->reset(new_window);
 }
 
+void ConfirmSlideDuringScrollCallback(WindowSlider* slider,
+                                      ui::EventType type,
+                                      const gfx::Vector2dF& delta) {
+  static float total_delta_x = 0;
+  if (type == ui::ET_GESTURE_SCROLL_BEGIN)
+    total_delta_x = 0;
+
+  if (type == ui::ET_GESTURE_SCROLL_UPDATE) {
+    total_delta_x += delta.x();
+    if (total_delta_x >= 70)
+      EXPECT_TRUE(slider->IsSlideInProgress());
+  } else {
+    EXPECT_FALSE(slider->IsSlideInProgress());
+  }
+}
+
+void ConfirmNoSlideDuringScrollCallback(WindowSlider* slider,
+                                        ui::EventType type,
+                                        const gfx::Vector2dF& delta) {
+  EXPECT_FALSE(slider->IsSlideInProgress());
+}
+
 // The window delegate does not receive any events.
 class NoEventWindowDelegate : public aura::test::TestWindowDelegate {
  public:
@@ -59,7 +89,8 @@ class WindowSliderDelegateTest : public WindowSlider::Delegate {
       : can_create_layer_(true),
         created_back_layer_(false),
         created_front_layer_(false),
-        slide_completed_(false),
+        fling_started_(false),
+        fling_completed_(false),
         slide_aborted_(false),
         slider_destroyed_(false) {
   }
@@ -69,7 +100,8 @@ class WindowSliderDelegateTest : public WindowSlider::Delegate {
     can_create_layer_ = true;
     created_back_layer_ = false;
     created_front_layer_ = false;
-    slide_completed_ = false;
+    fling_started_ = false;
+    fling_completed_ = false;
     slide_aborted_ = false;
     slider_destroyed_ = false;
   }
@@ -80,7 +112,8 @@ class WindowSliderDelegateTest : public WindowSlider::Delegate {
 
   bool created_back_layer() const { return created_back_layer_; }
   bool created_front_layer() const { return created_front_layer_; }
-  bool slide_completed() const { return slide_completed_; }
+  bool fling_started() const { return fling_started_; }
+  bool fling_completed() const { return fling_completed_; }
   bool slide_aborted() const { return slide_aborted_; }
   bool slider_destroyed() const { return slider_destroyed_; }
 
@@ -93,22 +126,26 @@ class WindowSliderDelegateTest : public WindowSlider::Delegate {
   }
 
   // Overridden from WindowSlider::Delegate:
-  virtual ui::Layer* CreateBackLayer() OVERRIDE {
+  virtual ui::Layer* OnSlideBackStartedCreateLayer() OVERRIDE {
     if (!can_create_layer_)
       return NULL;
     created_back_layer_ = true;
     return CreateLayerForTest();
   }
 
-  virtual ui::Layer* CreateFrontLayer() OVERRIDE {
+  virtual ui::Layer* OnSlideForwardStartedCreateLayer() OVERRIDE {
     if (!can_create_layer_)
       return NULL;
     created_front_layer_ = true;
     return CreateLayerForTest();
   }
 
-  virtual void OnWindowSlideComplete() OVERRIDE {
-    slide_completed_ = true;
+  virtual void OnWindowFlingCompleted() OVERRIDE {
+    fling_completed_ = true;
+  }
+
+  virtual void OnWindowFlingStarted() OVERRIDE {
+    fling_started_ = true;
   }
 
   virtual void OnWindowSlideAborted() OVERRIDE {
@@ -123,7 +160,8 @@ class WindowSliderDelegateTest : public WindowSlider::Delegate {
   bool can_create_layer_;
   bool created_back_layer_;
   bool created_front_layer_;
-  bool slide_completed_;
+  bool fling_started_;
+  bool fling_completed_;
   bool slide_aborted_;
   bool slider_destroyed_;
 
@@ -159,8 +197,8 @@ class WindowSliderDeleteOwnerOnComplete : public WindowSliderDelegateTest {
 
  private:
   // Overridden from WindowSlider::Delegate:
-  virtual void OnWindowSlideComplete() OVERRIDE {
-    WindowSliderDelegateTest::OnWindowSlideComplete();
+  virtual void OnWindowFlingCompleted() OVERRIDE {
+    WindowSliderDelegateTest::OnWindowFlingCompleted();
     delete owner_;
   }
 
@@ -180,12 +218,15 @@ TEST_F(WindowSliderTest, WindowSlideUsingGesture) {
   // Generate a horizontal overscroll.
   WindowSlider* slider =
       new WindowSlider(&slider_delegate, root_window(), window.get());
-  generator.GestureScrollSequence(gfx::Point(10, 10),
-                                  gfx::Point(180, 10),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(10, 10),
+      gfx::Point(180, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      10,
+      base::Bind(&ConfirmSlideDuringScrollCallback, slider));
   EXPECT_TRUE(slider_delegate.created_back_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
@@ -193,13 +234,16 @@ TEST_F(WindowSliderTest, WindowSlideUsingGesture) {
   slider_delegate.Reset();
   window->SetTransform(gfx::Transform());
 
-  // Generat a horizontal overscroll in the reverse direction.
-  generator.GestureScrollSequence(gfx::Point(180, 10),
-                                  gfx::Point(10, 10),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  // Generate a horizontal overscroll in the reverse direction.
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(180, 10),
+      gfx::Point(10, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      10,
+      base::Bind(&ConfirmSlideDuringScrollCallback, slider));
   EXPECT_TRUE(slider_delegate.created_front_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_back_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
@@ -207,12 +251,15 @@ TEST_F(WindowSliderTest, WindowSlideUsingGesture) {
   slider_delegate.Reset();
 
   // Generate a vertical overscroll.
-  generator.GestureScrollSequence(gfx::Point(10, 10),
-                                  gfx::Point(10, 80),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(10, 10),
+      gfx::Point(10, 80),
+      base::TimeDelta::FromMilliseconds(10),
+      10,
+      base::Bind(&ConfirmNoSlideDuringScrollCallback, slider));
   EXPECT_FALSE(slider_delegate.created_back_layer());
-  EXPECT_FALSE(slider_delegate.slide_completed());
+  EXPECT_FALSE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider->IsSlideInProgress());
@@ -220,14 +267,17 @@ TEST_F(WindowSliderTest, WindowSlideUsingGesture) {
 
   // Generate a horizontal scroll that starts overscroll, but doesn't scroll
   // enough to complete it.
-  generator.GestureScrollSequence(gfx::Point(10, 10),
-                                  gfx::Point(80, 10),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(10, 10),
+      gfx::Point(80, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      10,
+      base::Bind(&ConfirmSlideDuringScrollCallback, slider));
   EXPECT_TRUE(slider_delegate.created_back_layer());
   EXPECT_TRUE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.created_front_layer());
-  EXPECT_FALSE(slider_delegate.slide_completed());
+  EXPECT_FALSE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
   EXPECT_FALSE(slider->IsSlideInProgress());
   slider_delegate.Reset();
@@ -237,10 +287,11 @@ TEST_F(WindowSliderTest, WindowSlideUsingGesture) {
   EXPECT_TRUE(slider_delegate.slider_destroyed());
 }
 
-// Tests that the window slide is cancelled when a different type of event
+// Tests that the window slide is interrupted when a different type of event
 // happens.
 TEST_F(WindowSliderTest, WindowSlideIsCancelledOnEvent) {
   scoped_ptr<aura::Window> window(CreateNormalWindow(0, root_window(), NULL));
+  window->SetBounds(gfx::Rect(0, 0, 400, 400));
   WindowSliderDelegateTest slider_delegate;
 
   ui::Event* events[] = {
@@ -270,7 +321,8 @@ TEST_F(WindowSliderTest, WindowSlideIsCancelledOnEvent) {
     EXPECT_TRUE(slider_delegate.created_back_layer());
     EXPECT_TRUE(slider_delegate.slide_aborted());
     EXPECT_FALSE(slider_delegate.created_front_layer());
-    EXPECT_FALSE(slider_delegate.slide_completed());
+    EXPECT_FALSE(slider_delegate.fling_started());
+    EXPECT_FALSE(slider_delegate.fling_completed());
     EXPECT_FALSE(slider_delegate.slider_destroyed());
     slider_delegate.Reset();
   }
@@ -278,6 +330,118 @@ TEST_F(WindowSliderTest, WindowSlideIsCancelledOnEvent) {
   EXPECT_TRUE(slider_delegate.slider_destroyed());
 }
 
+// Tests that the window slide can continue after it is interrupted by another
+// event if the user continues scrolling.
+TEST_F(WindowSliderTest, WindowSlideInterruptedThenContinues) {
+  scoped_ptr<aura::Window> window(CreateNormalWindow(0, root_window(), NULL));
+  window->SetBounds(gfx::Rect(0, 0, 400, 400));
+  WindowSliderDelegateTest slider_delegate;
+
+  ui::ScopedAnimationDurationScaleMode normal_duration_(
+      ui::ScopedAnimationDurationScaleMode::NORMAL_DURATION);
+  ui::LayerAnimator* animator = window->layer()->GetAnimator();
+  gfx::AnimationContainerElement* element = animator;
+  animator->set_disable_timer_for_test(true);
+  ui::LayerAnimatorTestController test_controller(animator);
+
+  WindowSlider* slider =
+      new WindowSlider(&slider_delegate, root_window(), window.get());
+
+  ui::MouseEvent interrupt_event(ui::ET_MOUSE_MOVED,
+                                 gfx::Point(55, 10),
+                                 gfx::Point(55, 10),
+                                 0, 0);
+
+  aura::test::EventGenerator generator(root_window());
+
+  // Start the scroll sequence. Scroll forward so that |window|'s layer is the
+  // one animating.
+  const int kTouchId = 5;
+  ui::TouchEvent press(ui::ET_TOUCH_PRESSED,
+                       gfx::Point(10, 10),
+                       kTouchId,
+                       ui::EventTimeForNow());
+  generator.Dispatch(&press);
+
+  // First scroll event of the sequence.
+  ui::TouchEvent move1(ui::ET_TOUCH_MOVED,
+                       gfx::Point(100, 10),
+                       kTouchId,
+                       ui::EventTimeForNow());
+  generator.Dispatch(&move1);
+  EXPECT_TRUE(slider->IsSlideInProgress());
+  EXPECT_FALSE(animator->is_animating());
+  // Dispatch the event after the first scroll and confirm it interrupts the
+  // scroll and starts  the "reset slide" animation.
+  generator.Dispatch(&interrupt_event);
+  EXPECT_TRUE(slider->IsSlideInProgress());
+  EXPECT_TRUE(animator->is_animating());
+  EXPECT_TRUE(slider_delegate.created_back_layer());
+  // slide_aborted() should be false because the 'reset slide' animation
+  // hasn't completed yet.
+  EXPECT_FALSE(slider_delegate.slide_aborted());
+  EXPECT_FALSE(slider_delegate.created_front_layer());
+  EXPECT_FALSE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.fling_completed());
+  EXPECT_FALSE(slider_delegate.slider_destroyed());
+  slider_delegate.Reset();
+
+  // Second scroll event of the sequence.
+  ui::TouchEvent move2(ui::ET_TOUCH_MOVED,
+                       gfx::Point(200, 10),
+                       kTouchId,
+                       ui::EventTimeForNow());
+  generator.Dispatch(&move2);
+  // The second scroll should instantly cause the animation to complete.
+  EXPECT_FALSE(animator->is_animating());
+  EXPECT_FALSE(slider_delegate.created_back_layer());
+  // The ResetScroll() animation was completed, so now slide_aborted()
+  // should be true.
+  EXPECT_TRUE(slider_delegate.slide_aborted());
+
+  // Third scroll event of the sequence.
+  ui::TouchEvent move3(ui::ET_TOUCH_MOVED,
+                       gfx::Point(300, 10),
+                       kTouchId,
+                       ui::EventTimeForNow());
+  generator.Dispatch(&move3);
+  // The third scroll should re-start the sliding.
+  EXPECT_TRUE(slider->IsSlideInProgress());
+  EXPECT_TRUE(slider_delegate.created_back_layer());
+
+  // Generate the release event, finishing the scroll sequence.
+  ui::TouchEvent release(ui::ET_TOUCH_RELEASED,
+                         gfx::Point(300, 10),
+                         kTouchId,
+                         ui::EventTimeForNow());
+  generator.Dispatch(&release);
+  // When the scroll gesture ends, the "fling" animation should start.
+  EXPECT_TRUE(slider->IsSlideInProgress());
+  EXPECT_TRUE(animator->is_animating());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.created_front_layer());
+  EXPECT_FALSE(slider_delegate.fling_completed());
+  EXPECT_FALSE(slider_delegate.slider_destroyed());
+
+  // Progress the animator to complete the 'fling' animation.
+  base::TimeTicks start_time =  animator->last_step_time();
+  animator->OnThreadedAnimationStarted(cc::AnimationEvent(

[sadrul, 2014/03/19 20:21:18]

I don't think we are supposed to use cc::AnimationEvents directly. Can you look
into using StartThreadedAnimationsIfNeeded() instead?

[mfomitchev, 2014/03/20 15:10:06]

Done.

+      cc::AnimationEvent::Started,
+      0,
+      test_controller.GetRunningSequence(
+          ui::LayerAnimationElement::TRANSFORM)->animation_group_id(),
+      cc::Animation::Transform,
+      (start_time - base::TimeTicks()).InSecondsF()));
+  ui::ScopedLayerAnimationSettings settings(animator);
+  base::TimeDelta duration = settings.GetTransitionDuration();
+  element->Step(start_time + duration);
+  EXPECT_TRUE(slider_delegate.fling_completed());
+  EXPECT_FALSE(slider_delegate.slider_destroyed());
+
+  window.reset();
+  EXPECT_TRUE(slider_delegate.slider_destroyed());
+}
+
 // Tests that the slide works correctly when the owner of the window changes
 // during the duration of the slide.
 TEST_F(WindowSliderTest, OwnerWindowChangesDuringWindowSlide) {
@@ -308,44 +472,59 @@ TEST_F(WindowSliderTest, OwnerWindowChangesDuringWindowSlide) {
   EXPECT_NE(old_window, new_window);
 
   EXPECT_TRUE(slider_delegate.created_back_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
 }
 
+// If the delegate doesn't create the layer to show while sliding, WindowSlider
+// shouldn't start the slide or change delegate's state in any way in response
+// to user input.
 TEST_F(WindowSliderTest, NoSlideWhenLayerCantBeCreated) {
   scoped_ptr<aura::Window> window(CreateNormalWindow(0, root_window(), NULL));
   window->SetBounds(gfx::Rect(0, 0, 400, 400));
   WindowSliderDelegateTest slider_delegate;
   slider_delegate.SetCanCreateLayer(false);
+  WindowSlider* slider =
+      new WindowSlider(&slider_delegate, root_window(), window.get());
 
   aura::test::EventGenerator generator(root_window());
 
-  // Generate a horizontal overscroll.
-  scoped_ptr<WindowSlider> slider(
-      new WindowSlider(&slider_delegate, root_window(), window.get()));
-  generator.GestureScrollSequence(gfx::Point(10, 10),
-                                  gfx::Point(160, 10),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  // No slide in progress should be reported during scroll since the layer
+  // wasn't created.
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(10, 10),
+      gfx::Point(180, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      1,
+      base::Bind(&ConfirmNoSlideDuringScrollCallback, slider));
+
   EXPECT_FALSE(slider_delegate.created_back_layer());
-  EXPECT_FALSE(slider_delegate.slide_completed());
+  EXPECT_FALSE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
   window->SetTransform(gfx::Transform());
 
   slider_delegate.SetCanCreateLayer(true);
-  generator.GestureScrollSequence(gfx::Point(10, 10),
-                                  gfx::Point(160, 10),
-                                  base::TimeDelta::FromMilliseconds(10),
-                                  10);
+  generator.GestureScrollSequenceWithCallback(
+      gfx::Point(10, 10),
+      gfx::Point(180, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      10,
+      base::Bind(&ConfirmSlideDuringScrollCallback, slider));
   EXPECT_TRUE(slider_delegate.created_back_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
+
+  window.reset();
+  EXPECT_TRUE(slider_delegate.slider_destroyed());
 }
 
 // Tests that the owner window can be destroyed from |OnWindowSliderDestroyed()|
@@ -367,7 +546,8 @@ TEST_F(WindowSliderTest, OwnerIsDestroyedOnSliderDestroy) {
                                   base::TimeDelta::FromMilliseconds(10),
                                   10);
   EXPECT_TRUE(slider_delegate.created_back_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_FALSE(slider_delegate.slider_destroyed());
@@ -396,7 +576,8 @@ TEST_F(WindowSliderTest, OwnerIsDestroyedOnSlideComplete) {
                                   base::TimeDelta::FromMilliseconds(10),
                                   10);
   EXPECT_TRUE(slider_delegate.created_back_layer());
-  EXPECT_TRUE(slider_delegate.slide_completed());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
   EXPECT_FALSE(slider_delegate.created_front_layer());
   EXPECT_FALSE(slider_delegate.slide_aborted());
   EXPECT_TRUE(slider_delegate.slider_destroyed());
@@ -406,4 +587,85 @@ TEST_F(WindowSliderTest, OwnerIsDestroyedOnSlideComplete) {
   EXPECT_EQ(child_windows, root_window()->children().size());
 }
 
+// Test the scenario when two swipe gesture occur quickly one after another so
+// that the second swipe occurs while the transition animation triggered by the
+// first swipe is in progress.
+// The second swipe is supposed to instantly complete the animation caused by
+// the first swipe, ask the delegate to create a new layer, and animate it.
+TEST_F(WindowSliderTest, SwipeDuringSwipeAnimation) {
+  scoped_ptr<aura::Window> window(CreateNormalWindow(0, root_window(), NULL));
+  window->SetBounds(gfx::Rect(0, 0, 400, 400));
+  WindowSliderDelegateTest slider_delegate;
+  new WindowSlider(&slider_delegate, root_window(), window.get());
+
+  ui::ScopedAnimationDurationScaleMode normal_duration_(
+      ui::ScopedAnimationDurationScaleMode::NORMAL_DURATION);
+  ui::LayerAnimator* animator = window->layer()->GetAnimator();
+  gfx::AnimationContainerElement* element = animator;
+  animator->set_disable_timer_for_test(true);
+  ui::LayerAnimatorTestController test_controller(animator);
+
+  aura::test::EventGenerator generator(root_window());
+
+  // Swipe forward so that |window|'s layer is the one animating.
+  generator.GestureScrollSequence(
+      gfx::Point(10, 10),
+      gfx::Point(180, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      2);
+  ui::ScopedLayerAnimationSettings settings(animator);
+  base::TimeDelta duration = settings.GetTransitionDuration();
+  base::TimeTicks start_time1 =  animator->last_step_time();
+  EXPECT_TRUE(slider_delegate.created_back_layer());
+  EXPECT_FALSE(slider_delegate.slide_aborted());
+  EXPECT_FALSE(slider_delegate.created_front_layer());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_FALSE(slider_delegate.fling_completed());
+  EXPECT_FALSE(slider_delegate.slider_destroyed());
+  // Transform animation is a threaded animation, so it needs an extra kick to
+  // emulate the start.
+  animator->OnThreadedAnimationStarted(cc::AnimationEvent(
+      cc::AnimationEvent::Started,
+      0,
+      test_controller.GetRunningSequence(ui::LayerAnimationElement::TRANSFORM)->
+          animation_group_id(),
+      cc::Animation::Transform,
+      (start_time1 - base::TimeTicks()).InSecondsF()));
+
+  base::TimeTicks start_time2 = start_time1 + duration/2;
+  element->Step(start_time2);
+  EXPECT_FALSE(slider_delegate.fling_completed());
+  slider_delegate.Reset();
+  // Generate another horizontal swipe while the animation from the previous
+  // swipe is in progress.
+  generator.GestureScrollSequence(
+      gfx::Point(10, 10),
+      gfx::Point(180, 10),
+      base::TimeDelta::FromMilliseconds(10),
+      2);
+  // Performing the second swipe should instantly complete the slide started
+  // by the first swipe and create a new layer.
+  EXPECT_TRUE(slider_delegate.created_back_layer());
+  EXPECT_FALSE(slider_delegate.slide_aborted());
+  EXPECT_FALSE(slider_delegate.created_front_layer());
+  EXPECT_TRUE(slider_delegate.fling_started());
+  EXPECT_TRUE(slider_delegate.fling_completed());
+  EXPECT_FALSE(slider_delegate.slider_destroyed());
+  animator->OnThreadedAnimationStarted(cc::AnimationEvent(
+      cc::AnimationEvent::Started,
+      0,
+      test_controller.GetRunningSequence(ui::LayerAnimationElement::TRANSFORM)->
+          animation_group_id(),
+      cc::Animation::Transform,
+      (start_time2 - base::TimeTicks()).InSecondsF()));
+  slider_delegate.Reset();
+  element->Step(start_time2 + duration);
+  // The animation for the second slide should now be completed.
+  EXPECT_TRUE(slider_delegate.fling_completed());
+  slider_delegate.Reset();
+
+  window.reset();
+  EXPECT_TRUE(slider_delegate.slider_destroyed());
+}
+
 }  // namespace content