cc: Delay start of scrollbar animation setNeedsRedraw.

cc/layer_tree_host_impl.h

Index: cc/layer_tree_host_impl.h
diff --git a/cc/layer_tree_host_impl.h b/cc/layer_tree_host_impl.h
index b2b70e036193a8dc6bed54f7f37226756c09bb94..a6ecfa9559992b863aa0e5bb1f841cdaad3a31ba 100644
--- a/cc/layer_tree_host_impl.h
+++ b/cc/layer_tree_host_impl.h
@@ -65,6 +65,7 @@ class LayerTreeHostImplClient {
   virtual void SendManagedMemoryStats() = 0;
   virtual bool IsInsideDraw() = 0;
   virtual void RenewTreePriority() = 0;
+  virtual void RequestScrollbarAnimationOnImplThread(base::TimeDelta delay) = 0;
 };
 
 // LayerTreeHostImpl owns the LayerImpl trees as well as associated rendering
@@ -107,6 +108,8 @@ class CC_EXPORT LayerTreeHostImpl : public InputHandlerClient,
   virtual void setNeedsRedraw() OVERRIDE;
   virtual bool haveRootScrollLayer() const OVERRIDE;
 
+  void StartScrollbarAnimation(base::TimeTicks now);
+
   struct CC_EXPORT FrameData : public RenderPassSink {
     FrameData();
     ~FrameData();
@@ -381,6 +384,8 @@ class CC_EXPORT LayerTreeHostImpl : public InputHandlerClient,
 
   static LayerImpl* GetNonCompositedContentLayerRecursive(LayerImpl* layer);
 
+  void StartScrollbarAnimationRecursive(LayerImpl* layer, base::TimeTicks time);
+
   scoped_ptr<OutputSurface> output_surface_;
   scoped_ptr<ResourceProvider> resource_provider_;
   scoped_ptr<Renderer> renderer_;