Prevent overlay scrollbars expand or hover together

cc/input/single_scrollbar_animation_controller_thinning_unittest.cc

Index: cc/input/single_scrollbar_animation_controller_thinning_unittest.cc
diff --git a/cc/input/scrollbar_animation_controller_thinning_unittest.cc b/cc/input/single_scrollbar_animation_controller_thinning_unittest.cc
similarity index 89%
copy from cc/input/scrollbar_animation_controller_thinning_unittest.cc
copy to cc/input/single_scrollbar_animation_controller_thinning_unittest.cc
index 243602ba6adc177efe609a1c827e3358b5b7b54e..e1d9f2bb9705e1cb582bf0a988b137c29b2a42ad 100644
--- a/cc/input/scrollbar_animation_controller_thinning_unittest.cc
+++ b/cc/input/single_scrollbar_animation_controller_thinning_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "cc/input/scrollbar_animation_controller_thinning.h"
+#include "cc/input/single_scrollbar_animation_controller_thinning.h"
 
 #include "cc/layers/solid_color_scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_task_runner_provider.h"
@@ -22,16 +22,17 @@ namespace cc {
 namespace {
 
 // These constants are hard-coded and should match the values in
-// scrollbar_animation_controller_thinning.cc.
+// single_scrollbar_animation_controller_thinning.cc.
 const float kIdleThicknessScale = 0.4f;
 const float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
 
-class MockScrollbarAnimationControllerClient
+class MockSingleScrollbarAnimationControllerClient
     : public ScrollbarAnimationControllerClient {
  public:
-  explicit MockScrollbarAnimationControllerClient(LayerTreeHostImpl* host_impl)
+  explicit MockSingleScrollbarAnimationControllerClient(
+      LayerTreeHostImpl* host_impl)
       : host_impl_(host_impl) {}
-  virtual ~MockScrollbarAnimationControllerClient() {}
+  virtual ~MockSingleScrollbarAnimationControllerClient() {}
 
   void PostDelayedScrollbarAnimationTask(const base::Closure& start_fade,
                                          base::TimeDelta delay) override {
@@ -54,9 +55,9 @@ class MockScrollbarAnimationControllerClient
   LayerTreeHostImpl* host_impl_;
 };
 
-class ScrollbarAnimationControllerThinningTest : public testing::Test {
+class SingleScrollbarAnimationControllerThinningTest : public testing::Test {
  public:
-  ScrollbarAnimationControllerThinningTest()
+  SingleScrollbarAnimationControllerThinningTest()
       : host_impl_(&task_runner_provider_, &task_graph_runner_),
         client_(&host_impl_) {}
 
@@ -98,28 +99,30 @@ class ScrollbarAnimationControllerThinningTest : public testing::Test {
     scroll_layer_ptr->SetBounds(gfx::Size(200, 200));
     host_impl_.active_tree()->BuildLayerListAndPropertyTreesForTesting();
 
-    scrollbar_controller_ = ScrollbarAnimationControllerThinning::Create(
-        scroll_layer_ptr->id(), &client_, kDelayBeforeStarting,
+    scrollbar_controller_ = SingleScrollbarAnimationControllerThinning::Create(
+        scroll_layer_ptr->id(), HORIZONTAL, &client_, kDelayBeforeStarting,
         kResizeDelayBeforeStarting, kFadeDuration, kThinningDuration);
   }
 
   FakeImplTaskRunnerProvider task_runner_provider_;
   TestTaskGraphRunner task_graph_runner_;
   FakeLayerTreeHostImpl host_impl_;
-  std::unique_ptr<ScrollbarAnimationControllerThinning> scrollbar_controller_;
+  std::unique_ptr<SingleScrollbarAnimationControllerThinning>
+      scrollbar_controller_;
   LayerImpl* clip_layer_;
   SolidColorScrollbarLayerImpl* scrollbar_layer_;
-  NiceMock<MockScrollbarAnimationControllerClient> client_;
+  NiceMock<MockSingleScrollbarAnimationControllerClient> client_;
 };
 
 // Check initialization of scrollbar. Should start off invisible and thin.
-TEST_F(ScrollbarAnimationControllerThinningTest, Idle) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, Idle) {
   EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->Opacity());
-  EXPECT_FLOAT_EQ(0.4f, scrollbar_layer_->thumb_thickness_scale_factor());
+  EXPECT_FLOAT_EQ(kIdleThicknessScale,
+                  scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 // Check that scrollbar appears again when the layer becomes scrollable.
-TEST_F(ScrollbarAnimationControllerThinningTest, AppearOnResize) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, AppearOnResize) {
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
   scrollbar_controller_->DidScrollEnd();
@@ -137,7 +140,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, AppearOnResize) {
 }
 
 // Check that scrollbar disappears when the layer becomes non-scrollable.
-TEST_F(ScrollbarAnimationControllerThinningTest, HideOnResize) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, HideOnResize) {
   LayerImpl* scroll_layer = host_impl_.active_tree()->LayerById(1);
   ASSERT_TRUE(scroll_layer);
   EXPECT_EQ(gfx::Size(200, 200), scroll_layer->bounds());
@@ -169,7 +172,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, HideOnResize) {
 }
 
 // Scroll content. Confirm the scrollbar appears and fades out.
-TEST_F(ScrollbarAnimationControllerThinningTest, BasicAppearAndFadeOut) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, BasicAppearAndFadeOut) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -201,7 +204,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, BasicAppearAndFadeOut) {
 
 // Scroll content. Move the mouse near the scrollbar and confirm it becomes
 // thick. Ensure it fades out after that.
-TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearAndFadeOut) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, MoveNearAndFadeOut) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -215,7 +218,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearAndFadeOut) {
 
   // Now move the mouse near the scrollbar. This should cancel the currently
   // queued fading animation and start animating thickness.
-  scrollbar_controller_->DidMouseMoveNear(1);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
                   scrollbar_layer_->thumb_thickness_scale_factor());
@@ -236,7 +239,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearAndFadeOut) {
 
 // Scroll content. Move the mouse over the scrollbar and confirm it becomes
 // thick. Ensure it fades out after that.
-TEST_F(ScrollbarAnimationControllerThinningTest, MoveOverAndFadeOut) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, MoveOverAndFadeOut) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -250,7 +253,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveOverAndFadeOut) {
 
   // Now move the mouse over the scrollbar. This should cancel the currently
   // queued fading animation and start animating thickness.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
                   scrollbar_layer_->thumb_thickness_scale_factor());
@@ -271,7 +274,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveOverAndFadeOut) {
 
 // Make sure a scrollbar captured before the thickening animation doesn't try
 // to fade out.
-TEST_F(ScrollbarAnimationControllerThinningTest,
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
        DontFadeWhileCapturedBeforeThick) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
@@ -286,7 +289,7 @@ 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(HORIZONTAL, 0);
   scrollbar_controller_->DidMouseDown();
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
@@ -298,7 +301,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
 
 // Make sure a scrollbar captured after a thickening animation doesn't try to
 // fade out.
-TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeWhileCaptured) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, DontFadeWhileCaptured) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -311,7 +314,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeWhileCaptured) {
   EXPECT_FALSE(client_.start_fade().is_null());
 
   // Now move the mouse over the scrollbar and animate it until it's thick.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -329,7 +332,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, DontFadeWhileCaptured) {
 }
 
 // Make sure releasing a captured scrollbar causes it to fade out.
-TEST_F(ScrollbarAnimationControllerThinningTest, FadeAfterReleased) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, FadeAfterReleased) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -342,7 +345,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, FadeAfterReleased) {
   EXPECT_FALSE(client_.start_fade().is_null());
 
   // Now move the mouse over the scrollbar and capture it.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->DidMouseDown();
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
@@ -358,7 +361,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, FadeAfterReleased) {
 
 // Make sure moving near a scrollbar while it's fading out causes it to reset
 // the opacity and thicken.
-TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearScrollbarWhileFading) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       MoveNearScrollbarWhileFading) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -381,7 +385,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearScrollbarWhileFading) {
 
   // Now move the mouse near the scrollbar. It should reset opacity to 1
   // instantly and start animating to thick.
-  scrollbar_controller_->DidMouseMoveNear(1);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
                   scrollbar_layer_->thumb_thickness_scale_factor());
@@ -395,7 +399,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MoveNearScrollbarWhileFading) {
 
 // Make sure capturing a scrollbar while it's fading out causes it to reset the
 // opacity and thicken instantly.
-TEST_F(ScrollbarAnimationControllerThinningTest, CaptureScrollbarWhileFading) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       CaptureScrollbarWhileFading) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -404,7 +409,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, CaptureScrollbarWhileFading) {
   scrollbar_controller_->DidScrollEnd();
 
   // Move mouse over the scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -431,7 +436,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, CaptureScrollbarWhileFading) {
 }
 
 // Make sure we can't capture scrollbar that's completely faded out
-TEST_F(ScrollbarAnimationControllerThinningTest, TestCantCaptureWhenFaded) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       TestCantCaptureWhenFaded) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -440,7 +446,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, TestCantCaptureWhenFaded) {
   scrollbar_controller_->DidScrollEnd();
 
   // Move mouse over the scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -478,11 +484,11 @@ TEST_F(ScrollbarAnimationControllerThinningTest, TestCantCaptureWhenFaded) {
 
 // Initiate a scroll when the pointer is already near the scrollbar. It should
 // appear thick and remain thick.
-TEST_F(ScrollbarAnimationControllerThinningTest, ScrollWithMouseNear) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, ScrollWithMouseNear) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
-  scrollbar_controller_->DidMouseMoveNear(1);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
 
@@ -517,7 +523,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ScrollWithMouseNear) {
 
 // Move the pointer near the scrollbar. Confirm it gets thick and narrow when
 // moved away.
-TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, MouseNear) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
@@ -526,7 +532,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
   scrollbar_controller_->DidScrollUpdate(false);
   scrollbar_controller_->DidScrollEnd();
 
-  scrollbar_controller_->DidMouseMoveNear(1);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
@@ -539,7 +545,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
   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_->DidMouseMoveNear(HORIZONTAL, 2);
   scrollbar_controller_->Animate(time);
   time += base::TimeDelta::FromSeconds(10);
   scrollbar_controller_->Animate(time);
@@ -548,7 +554,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
 
   // Now move away from bar.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -559,7 +565,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseNear) {
 
 // Move the pointer over the scrollbar. Make sure it gets thick that it gets
 // thin when moved away.
-TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, MouseOver) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
@@ -568,7 +574,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
@@ -581,7 +587,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
 
   // Subsequent moves should not change anything.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += base::TimeDelta::FromSeconds(10);
   scrollbar_controller_->Animate(time);
@@ -591,7 +597,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
   // Moving off the scrollbar but still withing the "near" threshold should do
   // nothing.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation - 1.f);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation - 1.f);
   scrollbar_controller_->Animate(time);
   time += base::TimeDelta::FromSeconds(10);
   scrollbar_controller_->Animate(time);
@@ -600,7 +606,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
 
   // Now move away from bar.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -612,7 +618,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseOver) {
 // 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,
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
        MouseNearThenAwayWhileAnimating) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
@@ -622,7 +628,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
 
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
@@ -652,7 +658,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
   // 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_->DidMouseMoveNear(HORIZONTAL, 1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f - (1.0f - kIdleThicknessScale) / 2.0f,
                   scrollbar_layer_->thumb_thickness_scale_factor());
@@ -684,7 +690,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
 // 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,
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
        MouseCaptureAndReleaseOutOfBar) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
@@ -695,7 +701,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
   time += base::TimeDelta::FromSeconds(1);
 
   // Move over the scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kFadeDuration;
   scrollbar_controller_->Animate(time);
@@ -716,7 +722,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
   // Move outside the "near" threshold. Because the scrollbar is captured it
   // should remain thick.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->Opacity());
@@ -738,7 +744,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
 // 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) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       MouseCaptureAndReleaseOnBar) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
@@ -748,7 +755,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseCaptureAndReleaseOnBar) {
   time += base::TimeDelta::FromSeconds(1);
 
   // Move over scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -766,7 +773,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseCaptureAndReleaseOnBar) {
 
   // Move away from scrollbar. Nothing should change.
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->Animate(time);
   time += base::TimeDelta::FromSeconds(10);
@@ -776,7 +783,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseCaptureAndReleaseOnBar) {
 
   // Move over scrollbar and release. Since we're near the scrollbar, it should
   // remain thick.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->DidMouseUp();
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->Animate(time);
@@ -788,7 +795,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MouseCaptureAndReleaseOnBar) {
 
 // Move mouse on scrollbar and capture then move out of window. Confirm that
 // the bar stays thick.
-TEST_F(ScrollbarAnimationControllerThinningTest,
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
        MouseCapturedAndExitWindowFromScrollbar) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
@@ -799,7 +806,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
   time += base::TimeDelta::FromSeconds(1);
 
   // Move mouse over scrollbar.
-  scrollbar_controller_->DidMouseMoveNear(0);
+  scrollbar_controller_->DidMouseMoveNear(HORIZONTAL, 0);
   scrollbar_controller_->Animate(time);
   time += kThinningDuration;
   scrollbar_controller_->Animate(time);
@@ -822,7 +829,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest,
 }
 
 // Tests that the thickening/thinning effects are animated.
-TEST_F(ScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
@@ -833,7 +840,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
 
   // 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_->DidMouseMoveNear(HORIZONTAL, 1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
                   scrollbar_layer_->thumb_thickness_scale_factor());
@@ -850,7 +857,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
   // Move mouse away from scrollbar. Same check.
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->DidMouseMoveNear(
-      kDefaultMouseMoveDistanceToTriggerAnimation);
+      HORIZONTAL, kDefaultMouseMoveDistanceToTriggerAnimation);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
 
@@ -867,7 +874,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ThicknessAnimated) {
 
 // Tests that main thread scroll updates immediatley queue a fade animation
 // without requiring a ScrollEnd.
-TEST_F(ScrollbarAnimationControllerThinningTest, MainThreadScrollQueuesFade) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       MainThreadScrollQueuesFade) {
   ASSERT_TRUE(client_.start_fade().is_null());
 
   // A ScrollUpdate without a ScrollBegin indicates a main thread scroll update
@@ -891,7 +899,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, MainThreadScrollQueuesFade) {
 
 // Make sure that if the scroll update is as a result of a resize, we use the
 // resize delay time instead of the default one.
-TEST_F(ScrollbarAnimationControllerThinningTest, ResizeFadeDuration) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, ResizeFadeDuration) {
   ASSERT_TRUE(client_.delay().is_zero());
 
   scrollbar_controller_->DidScrollUpdate(true);
@@ -911,7 +919,7 @@ TEST_F(ScrollbarAnimationControllerThinningTest, ResizeFadeDuration) {
 }
 
 // Tests that the fade effect is animated.
-TEST_F(ScrollbarAnimationControllerThinningTest, FadeAnimated) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest, FadeAnimated) {
   // Scroll to make the scrollbars visible.
   scrollbar_controller_->DidScrollBegin();
   scrollbar_controller_->DidScrollUpdate(false);
@@ -942,7 +950,8 @@ TEST_F(ScrollbarAnimationControllerThinningTest, FadeAnimated) {
 }
 
 // Tests that the controller tells the client when the scrollbars hide/show.
-TEST_F(ScrollbarAnimationControllerThinningTest, NotifyChangedVisibility) {
+TEST_F(SingleScrollbarAnimationControllerThinningTest,
+       NotifyChangedVisibility) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);