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 6e90e93fc2913272e7a89bfde1b324240eb4e5d9..509e2778f370dcd4c2b6f8be842870273c0cf436 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(double delay) = 0;

[jamesr, 2013/03/14 19:52:01]

let's use base::TimeDeltas for delays.  With this signature I'm not sure what
unit the delay is supposed to be in

 };
 
 // LayerTreeHostImpl owns the LayerImpl trees as well as associated rendering
@@ -108,6 +109,8 @@ class CC_EXPORT LayerTreeHostImpl : public InputHandlerClient,
   virtual bool haveRootScrollLayer() const OVERRIDE;
   virtual float rootScrollLayerTotalScrollY() const OVERRIDE;
 
+  void StartScrollbarAnimation(base::TimeTicks now);
+
   struct CC_EXPORT FrameData : public RenderPassSink {
     FrameData();
     ~FrameData();
@@ -377,6 +380,8 @@ 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_;