Fix scrollbar fade animation scheduling.

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 097244c2a980fda58114932a747aacdb276f16ed..e13849986ea137496a237ee270e2315f7e5fd719 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -129,7 +129,7 @@ class LayerTreeHostImplTest : public testing::Test,
   virtual bool IsInsideDraw() OVERRIDE { return false; }
   virtual void RenewTreePriority() OVERRIDE {}
   virtual void RequestScrollbarAnimationOnImplThread(base::TimeDelta delay)
-      OVERRIDE {}
+      OVERRIDE { requested_scrollbar_animation_delay_ = delay; }
   virtual void DidActivatePendingTree() OVERRIDE {}
 
   void set_reduce_memory_result(bool reduce_memory_result) {
@@ -284,6 +284,7 @@ class LayerTreeHostImplTest : public testing::Test,
   bool did_request_redraw_;
   bool did_upload_visible_tile_;
   bool reduce_memory_result_;
+  base::TimeDelta requested_scrollbar_animation_delay_;
 };
 
 class TestWebGraphicsContext3DMakeCurrentFails
@@ -989,6 +990,101 @@ TEST_F(LayerTreeHostImplTest, PageScaleAnimationNoOp) {
   }
 }
 
+TEST_F(LayerTreeHostImplTest, ScrollbarLinearFadeScheduling) {
+  LayerTreeSettings settings;
+  settings.use_linear_fade_scrollbar_animator = true;
+  settings.scrollbar_linear_fade_delay_ms = 20;
+  settings.scrollbar_linear_fade_length_ms = 20;
+
+  host_impl_ = LayerTreeHostImpl::Create(settings,
+                                         this,
+                                         &proxy_,
+                                         &stats_instrumentation_);
+  host_impl_->InitializeRenderer(CreateOutputSurface());
+  host_impl_->SetViewportSize(gfx::Size(10, 10));
+
+  gfx::Size content_size(100, 100);
+  scoped_ptr<LayerImpl> root =
+      LayerImpl::Create(host_impl_->active_tree(), 1);
+  root->SetBounds(content_size);
+  root->SetContentBounds(content_size);
+
+  scoped_ptr<LayerImpl> scroll =
+      LayerImpl::Create(host_impl_->active_tree(), 2);
+  scroll->SetScrollable(true);
+  scroll->SetScrollOffset(gfx::Vector2d());
+  scroll->SetMaxScrollOffset(gfx::Vector2d(content_size.width(),
+                                           content_size.height()));
+  scroll->SetBounds(content_size);
+  scroll->SetContentBounds(content_size);
+
+  scoped_ptr<LayerImpl> contents =
+      LayerImpl::Create(host_impl_->active_tree(), 3);
+  contents->SetDrawsContent(true);
+  contents->SetBounds(content_size);
+  contents->SetContentBounds(content_size);
+
+  scoped_ptr<ScrollbarLayerImpl> scrollbar = ScrollbarLayerImpl::Create(
+      host_impl_->active_tree(),
+      4,
+      VERTICAL);
+  scroll->SetVerticalScrollbarLayer(scrollbar.get());
+
+  scroll->AddChild(contents.Pass());
+  root->AddChild(scroll.Pass());
+  root->AddChild(scrollbar.PassAs<LayerImpl>());
+
+  host_impl_->active_tree()->SetRootLayer(root.Pass());
+  host_impl_->active_tree()->DidBecomeActive();
+  InitializeRendererAndDrawFrame();
+
+  // If no scroll happened recently, StartScrollbarAnimation should have no
+  // effect.
+  host_impl_->StartScrollbarAnimation();
+  EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
+  EXPECT_FALSE(did_request_redraw_);
+
+  // After a scroll, a fade animation should be scheduled about 20ms from now
+  // (check greater than 10ms to avoid flakiness).
+  host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel);
+  host_impl_->ScrollEnd();
+  host_impl_->StartScrollbarAnimation();
+  EXPECT_LT(base::TimeDelta::FromMilliseconds(10),
+            requested_scrollbar_animation_delay_);
+  EXPECT_FALSE(did_request_redraw_);
+  requested_scrollbar_animation_delay_ = base::TimeDelta();
+
+  // After the fade begins, we should start getting redraws instead of a
+  // scheduled animation.
+  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(25));

[danakj, 2013/06/14 17:40:39]

This timing stuff is going to be a disaster on xp bots :/

Instead of this, can we hook into the animation controller to look for or listen
to events, so test things are working correctly that way?

One thought is that LayerImpl::DidBecomeActive is virtual so you could override
it and create a subclass of the linear fade animation controller that lets you
listen to things being called on it and respond.

You may see other ways to just make use of the LinearFade controller without
subclassing it to avoid these timing issues?

+  host_impl_->StartScrollbarAnimation();
+  EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
+  EXPECT_TRUE(did_request_redraw_);
+  did_request_redraw_ = false;
+
+  // If no scroll happened recently, StartScrollbarAnimation should have no
+  // effect.
+  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(25));
+  host_impl_->StartScrollbarAnimation();
+  EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
+  EXPECT_FALSE(did_request_redraw_);
+
+  // Setting the scroll offset outside a scroll should also cause the scrollbar
+  // to appear and to schedule a fade.
+  host_impl_->RootScrollLayer()->SetScrollOffset(gfx::Vector2d(5, 5));
+  host_impl_->StartScrollbarAnimation();
+  EXPECT_LT(base::TimeDelta::FromMilliseconds(10),
+            requested_scrollbar_animation_delay_);
+  EXPECT_FALSE(did_request_redraw_);
+  requested_scrollbar_animation_delay_ = base::TimeDelta();
+
+  // None of the above should have called CurrentFrameTimeTicks, so if we call
+  // it now we should get the current time.
+  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(10));
+  EXPECT_GT(base::TimeDelta::FromMilliseconds(5),
+            base::TimeTicks::Now() - host_impl_->CurrentFrameTimeTicks());
+}
+
 TEST_F(LayerTreeHostImplTest, CompositorFrameMetadata) {
   SetupScrollAndContentsLayers(gfx::Size(100, 100));
   host_impl_->SetViewportSize(gfx::Size(50, 50));