Prevent overlay scrollbars expand or hover together

cc/input/scrollbar_animation_controller_thinning_unittest.cc

Index: cc/input/scrollbar_animation_controller_thinning_unittest.cc
diff --git a/cc/input/scrollbar_animation_controller_thinning_unittest.cc b/cc/input/scrollbar_animation_controller_thinning_unittest.cc
index 9d2fee7152b3197771b3bce825f3b43280ce0d96..4274c02f3020ae3f18e3454f883f9d278415b729 100644
--- a/cc/input/scrollbar_animation_controller_thinning_unittest.cc
+++ b/cc/input/scrollbar_animation_controller_thinning_unittest.cc
@@ -60,6 +60,11 @@ class ScrollbarAnimationControllerThinningTest : public testing::Test {
       : host_impl_(&task_runner_provider_, &task_graph_runner_),
         client_(&host_impl_) {}
 
+  void ExpectScrollbarsOpacity(float opacity) {
+    EXPECT_FLOAT_EQ(opacity, v_scrollbar_layer_->Opacity());
+    EXPECT_FLOAT_EQ(opacity, h_scrollbar_layer_->Opacity());
+  }
+
  protected:
   const base::TimeDelta kDelayBeforeStarting = base::TimeDelta::FromSeconds(2);
   const base::TimeDelta kResizeDelayBeforeStarting =
@@ -71,29 +76,36 @@ class ScrollbarAnimationControllerThinningTest : public testing::Test {
     std::unique_ptr<LayerImpl> scroll_layer =
         LayerImpl::Create(host_impl_.active_tree(), 1);
     std::unique_ptr<LayerImpl> clip =
-        LayerImpl::Create(host_impl_.active_tree(), 3);
+        LayerImpl::Create(host_impl_.active_tree(), 2);
     clip_layer_ = clip.get();
     scroll_layer->SetScrollClipLayer(clip_layer_->id());
     LayerImpl* scroll_layer_ptr = scroll_layer.get();
 
-    const int kId = 2;
     const int kThumbThickness = 10;
     const int kTrackStart = 0;
     const bool kIsLeftSideVerticalScrollbar = false;
     const bool kIsOverlayScrollbar = true;
 
-    std::unique_ptr<SolidColorScrollbarLayerImpl> scrollbar =
+    std::unique_ptr<SolidColorScrollbarLayerImpl> h_scrollbar =
         SolidColorScrollbarLayerImpl::Create(
-            host_impl_.active_tree(), kId, HORIZONTAL, kThumbThickness,
+            host_impl_.active_tree(), 3, HORIZONTAL, kThumbThickness,
             kTrackStart, kIsLeftSideVerticalScrollbar, kIsOverlayScrollbar);
-    scrollbar_layer_ = scrollbar.get();
+    std::unique_ptr<SolidColorScrollbarLayerImpl> v_scrollbar =
+        SolidColorScrollbarLayerImpl::Create(
+            host_impl_.active_tree(), 4, VERTICAL, kThumbThickness, kTrackStart,
+            kIsLeftSideVerticalScrollbar, kIsOverlayScrollbar);
+    v_scrollbar_layer_ = v_scrollbar.get();
+    h_scrollbar_layer_ = h_scrollbar.get();
 
-    scroll_layer->test_properties()->AddChild(std::move(scrollbar));
+    scroll_layer->test_properties()->AddChild(std::move(v_scrollbar));
+    scroll_layer->test_properties()->AddChild(std::move(h_scrollbar));
     clip_layer_->test_properties()->AddChild(std::move(scroll_layer));
     host_impl_.active_tree()->SetRootLayerForTesting(std::move(clip));
 
-    scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
-    scrollbar_layer_->test_properties()->opacity_can_animate = true;
+    v_scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
+    h_scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
+    v_scrollbar_layer_->test_properties()->opacity_can_animate = true;
+    h_scrollbar_layer_->test_properties()->opacity_can_animate = true;
     clip_layer_->SetBounds(gfx::Size(100, 100));
     scroll_layer_ptr->SetBounds(gfx::Size(200, 200));
     host_impl_.active_tree()->BuildLayerListAndPropertyTreesForTesting();
@@ -108,54 +120,63 @@ class ScrollbarAnimationControllerThinningTest : public testing::Test {
   FakeLayerTreeHostImpl host_impl_;
   std::unique_ptr<ScrollbarAnimationControllerThinning> scrollbar_controller_;
   LayerImpl* clip_layer_;
-  SolidColorScrollbarLayerImpl* scrollbar_layer_;
+  SolidColorScrollbarLayerImpl* v_scrollbar_layer_;
+  SolidColorScrollbarLayerImpl* h_scrollbar_layer_;
   NiceMock<MockScrollbarAnimationControllerClient> client_;
 };
 
-// Check initialization of scrollbar. Should start off invisible and thin.
+// Check initialization of scrollbar. Should start of invisible and thin.

[weiliangc, 2017/01/26 23:13:54]

nit: not need to change comment.

 TEST_F(ScrollbarAnimationControllerThinningTest, Idle) {
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(0.4f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_TRUE(scrollbar_controller_->ScrollbarsHidden());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 // Check that scrollbar appears again when the layer becomes scrollable.
 TEST_F(ScrollbarAnimationControllerThinningTest, AppearOnResize) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
   scrollbar_controller_->DidScrollEnd();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 
   // Make the Layer non-scrollable, scrollbar disappears.
   clip_layer_->SetBounds(gfx::Size(200, 200));
   scrollbar_controller_->DidScrollUpdate(false);
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
 
   // Make the layer scrollable, scrollbar appears again.
   clip_layer_->SetBounds(gfx::Size(100, 100));
   scrollbar_controller_->DidScrollUpdate(false);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 }
 
 // Check that scrollbar disappears when the layer becomes non-scrollable.
 TEST_F(ScrollbarAnimationControllerThinningTest, HideOnResize) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
   LayerImpl* scroll_layer = host_impl_.active_tree()->LayerById(1);
   ASSERT_TRUE(scroll_layer);
   EXPECT_EQ(gfx::Size(200, 200), scroll_layer->bounds());
 
-  EXPECT_EQ(HORIZONTAL, scrollbar_layer_->orientation());
-
-  // Shrink along X axis, horizontal scrollbar should appear.
+  // Shrink along X axis, Horizontal Scrollbar should appear.

[weiliangc, 2017/01/26 23:13:54]

nit: not need to change comment.

   clip_layer_->SetBounds(gfx::Size(100, 200));
   EXPECT_EQ(gfx::Size(100, 200), clip_layer_->bounds());
 
   scrollbar_controller_->DidScrollBegin();
 
   scrollbar_controller_->DidScrollUpdate(false);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  EXPECT_FLOAT_EQ(1, h_scrollbar_layer_->Opacity());
 
   scrollbar_controller_->DidScrollEnd();
 
-  // Shrink along Y axis and expand along X, horizontal scrollbar
+  // Shrink along Y axis and expand along X, Horizontal Scrollbar

[weiliangc, 2017/01/26 23:13:54]

nit: not need to change comment.

   // should disappear.
   clip_layer_->SetBounds(gfx::Size(200, 100));
   EXPECT_EQ(gfx::Size(200, 100), clip_layer_->bounds());
@@ -163,7 +184,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, HideOnResize) {
   scrollbar_controller_->DidScrollBegin();
 
   scrollbar_controller_->DidScrollUpdate(false);
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  EXPECT_FLOAT_EQ(0.0f, h_scrollbar_layer_->Opacity());
 
   scrollbar_controller_->DidScrollEnd();
 }
@@ -173,18 +194,22 @@ TEST_F(ScrollbarAnimationControllerThinningTest, BasicAppearAndFadeOut) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
-  // Scrollbar should be invisible by default.
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  // Scrollbar should be invisible.
+  ExpectScrollbarsOpacity(0);
+  EXPECT_TRUE(scrollbar_controller_->ScrollbarsHidden());
 
   // Scrollbar should appear only on scroll update.
   scrollbar_controller_->DidScrollBegin();
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_TRUE(scrollbar_controller_->ScrollbarsHidden());
 
   scrollbar_controller_->DidScrollUpdate(false);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FALSE(scrollbar_controller_->ScrollbarsHidden());
 
   scrollbar_controller_->DidScrollEnd();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FALSE(scrollbar_controller_->ScrollbarsHidden());
 
   // An animation should have been enqueued.
   EXPECT_EQ(kDelayBeforeStarting, client_.delay());
@@ -196,7 +221,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, BasicAppearAndFadeOut) {
   time += kFadeDuration;
   scrollbar_controller_->Animate(time);
 
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_TRUE(scrollbar_controller_->ScrollbarsHidden());
 }
 
 // Scroll content. Move the mouse near the scrollbar and confirm it becomes
@@ -216,18 +242,22 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearAndDontFadeOut) {
 
   // Now move the mouse near the scrollbar. This should cancel the currently
   // queued fading animation and start animating thickness.
-  scrollbar_controller_->DidMouseMoveNear(1);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_TRUE(client_.start_fade().IsCancelled());
 
-  // Scrollbar should become thick.
+  // Vertical Scrollbar should become thick.
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Mouse is still near the Scrollbar. Once the thickness animation is
   // complete, the queued delayed fade animation should be either cancelled or
@@ -253,22 +283,26 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveOverAndDontFadeOut) {
 
   // Now move the mouse over the scrollbar. This should cancel the currently
   // queued fading animation and start animating thickness.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_TRUE(client_.start_fade().IsCancelled());
 
-  // Scrollbar should become thick.
+  // Vertical Scrollbar should become thick.
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Mouse is still over the Scrollbar. Once the thickness animation is
-  // complete, the queued delayed fade animation should be either null or
-  // cancelled.
+  // complete, the queued delayed fade animation should be either cancelled or
+  // null.
   EXPECT_TRUE(client_.start_fade().is_null() ||
               client_.start_fade().IsCancelled());
 }
@@ -290,14 +324,52 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
 
   // Now move the mouse over the scrollbar and capture it. It should become
   // thick without need for an animation.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
   scrollbar_controller_->DidMouseDown();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // The fade animation should have been cleared or cancelled.
+  EXPECT_TRUE(client_.start_fade().is_null() ||
+              client_.start_fade().IsCancelled());
+}
+
+// Make sure a scrollbar captured then move mouse away doesn't try to fade out.
+TEST_F(ScrollbarAnimationControllerThinningTest,
+       DontFadeWhileCapturedThenAway) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
+  scrollbar_controller_->DidScrollBegin();
+  scrollbar_controller_->DidScrollUpdate(false);
+  scrollbar_controller_->DidScrollEnd();
+
+  // An animation should have been enqueued.
+  EXPECT_EQ(kDelayBeforeStarting, client_.delay());
+  EXPECT_FALSE(client_.start_fade().is_null());
+
+  // Now move the mouse over the scrollbar and capture it. It should become
+  // thick without need for an animation.
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
+  scrollbar_controller_->DidMouseDown();
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // The fade animation should have been cleared or cancelled.
   EXPECT_TRUE(client_.start_fade().is_null() ||
               client_.start_fade().IsCancelled());
+
+  // Then move mouse away, The fade animation should have been cleared or
+  // cancelled.
+  scrollbar_controller_->DidMouseMoveNear(
+      VERTICAL, kDefaultMouseMoveDistanceToTriggerAnimation);
+
+  EXPECT_TRUE(client_.start_fade().is_null() ||
+              client_.start_fade().IsCancelled());
 }
 
 // Make sure a scrollbar captured after a thickening animation doesn't try to
@@ -316,12 +388,14 @@ TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeWhileCaptured) {
   EXPECT_FALSE(client_.start_fade().IsCancelled());
 
   // Now move the mouse over the scrollbar and animate it until it's thick.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Since the mouse is over the scrollbar, it should either clear or cancel the
   // queued fade.
@@ -351,10 +425,12 @@ TEST_F(ScrollbarAnimationControllerThinningTest, FadeAfterReleasedFar) {
   EXPECT_FALSE(client_.start_fade().IsCancelled());
 
   // Now move the mouse over the scrollbar and capture it.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
   scrollbar_controller_->DidMouseDown();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Since the mouse is still near the scrollbar, the queued fade should be
   // either null or cancelled.
@@ -363,17 +439,21 @@ TEST_F(ScrollbarAnimationControllerThinningTest, FadeAfterReleasedFar) {
 
   // Now move the mouse away from the scrollbar and release it.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation + 1);
+      VERTICAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   scrollbar_controller_->DidMouseUp();
 
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // The thickness animation is complete, a fade out must be queued.
   EXPECT_FALSE(client_.start_fade().is_null());
@@ -396,10 +476,12 @@ TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeAfterReleasedNear) {
   EXPECT_FALSE(client_.start_fade().IsCancelled());
 
   // Now move the mouse over the scrollbar and capture it.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
   scrollbar_controller_->DidMouseDown();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Since the mouse is over the scrollbar, the queued fade must be either
   // null or cancelled.
@@ -410,8 +492,10 @@ TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeAfterReleasedNear) {
   scrollbar_controller_->DidMouseUp();
   EXPECT_TRUE(client_.start_fade().is_null() ||
               client_.start_fade().IsCancelled());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 // Make sure moving near a scrollbar while it's fading out causes it to reset
@@ -430,25 +514,29 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearScrollbarWhileFading) {
   client_.start_fade().Run();
 
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 
   // Proceed half way through the fade out animation.
   time += kFadeDuration / 2;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.5f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(.5f);
 
   // Now move the mouse near the scrollbar. It should reset opacity to 1
   // instantly and start animating to thick.
-  scrollbar_controller_->DidMouseMoveNear(1);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 // Make sure we can't capture scrollbar that's completely faded out.
@@ -465,38 +553,41 @@ TEST_F(ScrollbarAnimationControllerThinningTest, TestCantCaptureWhenFaded) {
   EXPECT_FALSE(client_.start_fade().IsCancelled());
   client_.start_fade().Run();
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 
   // Fade the scrollbar out completely.
   time += kFadeDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
 
   // Move mouse over the scrollbar. It shouldn't thicken the scrollbar since
   // it's completely faded out.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   client_.start_fade().Reset();
 
   // Now try to capture the scrollbar. It shouldn't do anything since it's
   // completely faded out.
   scrollbar_controller_->DidMouseDown();
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_TRUE(client_.start_fade().is_null());
 
   // Similarly, releasing the scrollbar should have no effect.
   scrollbar_controller_->DidMouseUp();
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_TRUE(client_.start_fade().is_null());
 }
 
@@ -506,21 +597,22 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ScrollWithMouseNear) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
-  scrollbar_controller_->DidMouseMoveNear(1);
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
 
   // Since the scrollbar isn't visible yet (because we haven't scrolled), we
   // shouldn't have applied the thickening.
   scrollbar_controller_->Animate(time);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
 
   // Now that we've received a scroll, we should be thick without an animation.
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
+  ExpectScrollbarsOpacity(1);
 
   // An animation for the fade should be either null or cancelled, since
   // mouse is still near the scrollbar.
@@ -530,364 +622,18 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ScrollWithMouseNear) {
               client_.start_fade().IsCancelled());
 
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Scrollbar should still be thick and visible.
-  time += kFadeDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// Move the pointer near the scrollbar. Confirm it gets thick and narrow when
-// moved away.
-TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  scrollbar_controller_->DidMouseMoveNear(1);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Should animate to thickened.
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Subsequent moves within the nearness threshold should not change anything.
-  scrollbar_controller_->DidMouseMoveNear(2);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Now move away from bar.
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-}
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 
-// Move the pointer over the scrollbar. Make sure it gets thick that it gets
-// thin when moved away.
-TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Should animate to thickened.
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Subsequent moves should not change anything.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Moving off the scrollbar but still withing the "near" threshold should do
-  // nothing.
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation - 1.f);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Now move away from bar.
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// First move the pointer over the scrollbar off of it. Make sure the thinning
-// animation kicked off in DidMouseMoveOffScrollbar gets overridden by the
-// thickening animation in the DidMouseMoveNear call.
-TEST_F(ScrollbarAnimationControllerThinningTest,
-       MouseNearThenAwayWhileAnimating) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Should animate to thickened.
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // This is tricky. The DidMouseLeave() is sent before the
-  // subsequent DidMouseMoveNear(), if the mouse moves in that direction.
-  // This results in the thumb thinning. We want to make sure that when the
-  // thumb starts expanding it doesn't first narrow to the idle thinness.
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->DidMouseLeave();
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Let the animation run half of the way through the thinning animation.
-  time += kThinningDuration / 2;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Now we get a notification for the mouse moving over the scroller. The
-  // animation is reset to the thickening direction but we won't start
-  // thickening until the new animation catches up to the current thickness.
-  scrollbar_controller_->DidMouseMoveNear(1);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Until we reach the half way point, the animation will have no effect.
-  time += kThinningDuration / 4;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  time += kThinningDuration / 4;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // We're now at three quarters of the way through so it should now started
-  // thickening again.
-  time += kThinningDuration / 4;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(kIdleThicknessScale + 3 * (1.0f - kIdleThicknessScale) / 4.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // And all the way to the end.
-  time += kThinningDuration / 4;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// First move the pointer on the scrollbar, then press it, then away.
-// Confirm that the bar gets thick. Then mouse up. Confirm that
-// the bar gets thin.
-TEST_F(ScrollbarAnimationControllerThinningTest,
-       MouseCaptureAndReleaseOutOfBar) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  // Move over the scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
+  // Scrollbar should still be thick and visible.
   time += kFadeDuration;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Capture
-  scrollbar_controller_->DidMouseDown();
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Should stay thick for a while.
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-
-  // Move outside the "near" threshold. Because the scrollbar is captured it
-  // should remain thick.
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Release.
-  scrollbar_controller_->DidMouseUp();
-
-  // Should become thin.
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// First move the pointer on the scrollbar, then press it, then away.  Confirm
-// that the bar gets thick. Then move point on the scrollbar and mouse up.
-// Confirm that the bar stays thick.
-TEST_F(ScrollbarAnimationControllerThinningTest, MouseCaptureAndReleaseOnBar) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  // Move over scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Capture. Nothing should change.
-  scrollbar_controller_->DidMouseDown();
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Move away from scrollbar. Nothing should change.
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Move over scrollbar and release. Since we're near the scrollbar, it should
-  // remain thick.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->DidMouseUp();
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->Animate(time);
-  time += base::TimeDelta::FromSeconds(10);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// Move mouse on scrollbar and capture then move out of window. Confirm that
-// the bar stays thick.
-TEST_F(ScrollbarAnimationControllerThinningTest,
-       MouseCapturedAndExitWindowFromScrollbar) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  // Move mouse over scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Capture.
-  scrollbar_controller_->DidMouseDown();
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Move out of window. Since the scrollbar is capture, it shouldn't change in
-  // any way.
-  scrollbar_controller_->DidMouseLeave();
-  scrollbar_controller_->Animate(time);
-  time += kThinningDuration;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-}
-
-// Tests that the thickening/thinning effects are animated.
-TEST_F(ScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
-  // Scroll to make the scrollbars visible.
-  scrollbar_controller_->DidScrollBegin();
-  scrollbar_controller_->DidScrollUpdate(false);
-  scrollbar_controller_->DidScrollEnd();
-
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
-  // Move mouse near scrollbar. Test that at half the duration time, the
-  // thickness is half way through its animation.
-  scrollbar_controller_->DidMouseMoveNear(1);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  time += kThinningDuration / 2;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(kIdleThicknessScale + (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  time += kThinningDuration / 2;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  // Move mouse away from scrollbar. Same check.
-  time += base::TimeDelta::FromSeconds(1);
-  scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
-
-  time += kThinningDuration / 2;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
-
-  time += kThinningDuration / 2;
-  scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(kIdleThicknessScale,
-                  scrollbar_layer_->thumb_thickness_scale_factor());
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 // Tests that main thread scroll updates immediatley queue a fade animation
@@ -937,33 +683,33 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ResizeFadeDuration) {
 
 // Tests that the fade effect is animated.
 TEST_F(ScrollbarAnimationControllerThinningTest, FadeAnimated) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
   scrollbar_controller_->DidScrollEnd();
 
   // Appearance is instant.
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 
   // An animation should have been enqueued.
   EXPECT_EQ(kDelayBeforeStarting, client_.delay());
   EXPECT_FALSE(client_.start_fade().is_null());
   client_.start_fade().Run();
 
-  base::TimeTicks time;
-  time += base::TimeDelta::FromSeconds(1);
-
   // Test that at half the fade duration time, the opacity is at half.
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(1);
 
   time += kFadeDuration / 2;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.5f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(.5f);
 
   time += kFadeDuration / 2;
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
 }
 
 // Tests that the controller tells the client when the scrollbars hide/show.
@@ -996,14 +742,14 @@ TEST_F(ScrollbarAnimationControllerThinningTest, NotifyChangedVisibility) {
   time += kFadeDuration / 4;
   EXPECT_FALSE(scrollbar_controller_->ScrollbarsHidden());
   scrollbar_controller_->Animate(time);
-  EXPECT_FLOAT_EQ(0.25f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(.25f);
   Mock::VerifyAndClearExpectations(&client_);
 
   EXPECT_CALL(client_, DidChangeScrollbarVisibility()).Times(1);
   time += kFadeDuration / 4;
   scrollbar_controller_->Animate(time);
   EXPECT_TRUE(scrollbar_controller_->ScrollbarsHidden());
-  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
+  ExpectScrollbarsOpacity(0);
   Mock::VerifyAndClearExpectations(&client_);
 
   // Calling DidScrollUpdate without a begin (i.e. update from commit) should
@@ -1014,5 +760,191 @@ TEST_F(ScrollbarAnimationControllerThinningTest, NotifyChangedVisibility) {
   Mock::VerifyAndClearExpectations(&client_);
 }
 
+// Move the pointer near each scrollbar. Confirm it gets thick and narrow when
+// moved away.
+TEST_F(ScrollbarAnimationControllerThinningTest, MouseNearEach) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
+  // Scroll to make the scrollbars visible.
+  scrollbar_controller_->DidScrollBegin();
+  scrollbar_controller_->DidScrollUpdate(false);
+  scrollbar_controller_->DidScrollEnd();
+
+  // Near Vertical Scrollbar
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Should animate to thickened.
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Subsequent moves within the nearness threshold should not change anything.
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 2);
+  scrollbar_controller_->Animate(time);
+  time += base::TimeDelta::FromSeconds(10);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Now move away from bar.
+  scrollbar_controller_->DidMouseMoveNear(
+      VERTICAL, kDefaultMouseMoveDistanceToTriggerAnimation);
+  scrollbar_controller_->Animate(time);
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Near Horizontal Scrollbar
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 2);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Should animate to thickened.
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(1, h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Subsequent moves within the nearness threshold should not change anything.
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
+  scrollbar_controller_->Animate(time);
+  time += base::TimeDelta::FromSeconds(10);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(1, h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Now move away from bar.
+  scrollbar_controller_->DidMouseMoveNear(
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
+  scrollbar_controller_->Animate(time);
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // An animation should have been enqueued.
+  EXPECT_FALSE(client_.start_fade().is_null());
+  EXPECT_EQ(kDelayBeforeStarting, client_.delay());
+}
+
+// Move mouse near both scrollbars at the same time.
+TEST_F(ScrollbarAnimationControllerThinningTest, MouseNearBoth) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
+  // Scroll to make the scrollbars visible.
+  scrollbar_controller_->DidScrollBegin();
+  scrollbar_controller_->DidScrollUpdate(false);
+  scrollbar_controller_->DidScrollEnd();
+
+  // Near both Scrollbar
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Should animate to thickened.
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(1, v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(1, h_scrollbar_layer_->thumb_thickness_scale_factor());
+}
+
+// Move mouse from one to the other scrollbar before animation is finished, then
+// away before animation finished.
+TEST_F(ScrollbarAnimationControllerThinningTest,
+       MouseNearOtherBeforeAnimationFinished) {
+  base::TimeTicks time;
+  time += base::TimeDelta::FromSeconds(1);
+
+  // Scroll to make the scrollbars visible.
+  scrollbar_controller_->DidScrollBegin();
+  scrollbar_controller_->DidScrollUpdate(false);
+  scrollbar_controller_->DidScrollEnd();
+
+  // Near Vertical Scrollbar.
+  scrollbar_controller_->DidMouseMoveNear(VERTICAL, 1);
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Vertical Scrollbar animate to half thickened.
+  time += kThinningDuration / 2;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale + (1.0f - kIdleThicknessScale) / 2,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Away Vertical Scrollbar and near Horizontal Scrollbar.
+  scrollbar_controller_->DidMouseMoveNear(
+      VERTICAL, kDefaultMouseMoveDistanceToTriggerAnimation);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
+  scrollbar_controller_->Animate(time);
+
+  // Vertical Scrollbar animate to thin. Horizontal Scrollbar animate to
+  // thickened.
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(1, h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // Away Horizontal Scrollbar.
+  scrollbar_controller_->DidMouseMoveNear(
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
+  scrollbar_controller_->Animate(time);
+
+  // Horizontal Scrollbar animate to thin.
+  time += kThinningDuration;
+  scrollbar_controller_->Animate(time);
+  ExpectScrollbarsOpacity(1);
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  v_scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  h_scrollbar_layer_->thumb_thickness_scale_factor());
+
+  // An animation should have been enqueued.
+  EXPECT_FALSE(client_.start_fade().is_null());
+  EXPECT_EQ(kDelayBeforeStarting, client_.delay());
+}
+
 }  // namespace
 }  // namespace cc