change overlay scrollbar hover show to hover fade in

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index c7f6e98bea11c02d78ef280cbe3be69432b196e6..cea1d2fa50cbf1dc18141cb874edccb03955ed0b 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -2870,12 +2870,10 @@ class LayerTreeHostImplTestScrollbarAnimation : public LayerTreeHostImplTest {
   void RunTest(LayerTreeSettings::ScrollbarAnimator animator) {
     LayerTreeSettings settings = DefaultSettings();
     settings.scrollbar_animator = animator;
-    settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
-    settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(20);
     settings.scrollbar_fade_out_resize_delay =
         base::TimeDelta::FromMilliseconds(20);
-    settings.scrollbar_fade_out_duration =
-        base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(20);
 
     // If no animator is set, scrollbar won't show and no animation is expected.
     bool expecting_animations = animator != LayerTreeSettings::NO_ANIMATOR;
@@ -3094,10 +3092,8 @@ class LayerTreeHostImplTestScrollbarOpacity : public LayerTreeHostImplTest {
   void RunTest(LayerTreeSettings::ScrollbarAnimator animator) {
     LayerTreeSettings settings = DefaultSettings();
     settings.scrollbar_animator = animator;
-    settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
-    settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
-    settings.scrollbar_fade_out_duration =
-        base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(20);
     gfx::Size content_size(100, 100);
 
     // If no animator is set, scrollbar won't show and no animation is expected.
@@ -3193,9 +3189,8 @@ TEST_F(LayerTreeHostImplTestScrollbarOpacity, NoAnimator) {
 TEST_F(LayerTreeHostImplTest, ScrollbarVisibilityChangeCausesRedrawAndCommit) {
   LayerTreeSettings settings = DefaultSettings();
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;
-  settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
-  settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
-  settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(20);
   gfx::Size content_size(100, 100);
 
   CreateHostImpl(settings, CreateCompositorFrameSink());
@@ -3227,14 +3222,14 @@ TEST_F(LayerTreeHostImplTest, ScrollbarVisibilityChangeCausesRedrawAndCommit) {
 
     base::TimeTicks fake_now = base::TimeTicks::Now();
     scrollbar_controller->Animate(fake_now);
-    fake_now += settings.scrollbar_fade_out_delay;
+    fake_now += settings.scrollbar_fade_delay;
     scrollbar_controller->Animate(fake_now);
 
     ASSERT_TRUE(scrollbar_controller->ScrollbarsHidden());
   }
 
-  // Move the mouse over the scrollbar region. This should post a delayed show
-  // task. Execute it to show the scrollbars.
+  // Move the mouse over the scrollbar region. This should post a delayed fade
+  // in task. Execute it to show the scrollbars.
   {
     animation_task_ = base::Closure();
     scrollbar_controller->DidMouseMoveNear(VERTICAL, 0);
@@ -3242,13 +3237,19 @@ TEST_F(LayerTreeHostImplTest, ScrollbarVisibilityChangeCausesRedrawAndCommit) {
     ASSERT_FALSE(animation_task_.IsCancelled());
   }
 
-  // The show task should cause the scrollbars to show. Ensure that we
+  // The fade in task should cause the scrollbars to show. Ensure that we
   // requested a redraw and a commit.
   {
     did_request_redraw_ = false;
     did_request_commit_ = false;
     ASSERT_TRUE(scrollbar_controller->ScrollbarsHidden());
     animation_task_.Run();
+
+    base::TimeTicks fake_now = base::TimeTicks::Now();
+    scrollbar_controller->Animate(fake_now);
+    fake_now += settings.scrollbar_fade_duration;
+    scrollbar_controller->Animate(fake_now);
+
     ASSERT_FALSE(scrollbar_controller->ScrollbarsHidden());
     EXPECT_TRUE(did_request_redraw_);
     EXPECT_TRUE(did_request_commit_);
@@ -3292,9 +3293,8 @@ TEST_F(LayerTreeHostImplTest, ScrollbarInnerLargerThanOuter) {
 TEST_F(LayerTreeHostImplTest, ScrollbarRegistration) {
   LayerTreeSettings settings = DefaultSettings();
   settings.scrollbar_animator = LayerTreeSettings::ANDROID_OVERLAY;
-  settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
-  settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
-  settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(20);
   CreateHostImpl(settings, CreateCompositorFrameSink());
 
   gfx::Size viewport_size(300, 200);
@@ -3422,9 +3422,8 @@ TEST_F(LayerTreeHostImplTest, ScrollbarRegistration) {
 void LayerTreeHostImplTest::SetupMouseMoveAtWithDeviceScale(
     float device_scale_factor) {
   LayerTreeSettings settings = DefaultSettings();
-  settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(500);
-  settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(500);
-  settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(300);
+  settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(500);
+  settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(300);
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;
 
   gfx::Size viewport_size(300, 200);
@@ -12051,9 +12050,8 @@ TEST_F(LayerTreeHostImplTest, RecomputeGpuRasterOnCompositorFrameSinkChange) {
 void LayerTreeHostImplTest::SetupMouseMoveAtTestScrollbarStates(
     bool main_thread_scrolling) {
   LayerTreeSettings settings = DefaultSettings();
-  settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(500);
-  settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(500);
-  settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(300);
+  settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(500);
+  settings.scrollbar_fade_duration = base::TimeDelta::FromMilliseconds(300);
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;
 
   gfx::Size viewport_size(300, 200);