Hook up ui::Compositor to Display's BeginFrameSource

cc/output/output_surface_client.h

Index: cc/output/output_surface_client.h
diff --git a/cc/output/output_surface_client.h b/cc/output/output_surface_client.h
index 8f7f36ee2044273a24cb077fefe39c54fda819d8..dae73582ced65317a09a701bbb5cf0e51bb23755 100644
--- a/cc/output/output_surface_client.h
+++ b/cc/output/output_surface_client.h
@@ -18,13 +18,20 @@ class Transform;
 
 namespace cc {
 
+class BeginFrameSource;
 class CompositorFrameAck;
 struct ManagedMemoryPolicy;
 
 class CC_EXPORT OutputSurfaceClient {
  public:
+  // TODO(enne): Remove this in favor of using SetBeginFrameSource.
   virtual void CommitVSyncParameters(base::TimeTicks timebase,
                                      base::TimeDelta interval) = 0;
+  // Pass the begin frame source for the client to observe.  Client does not own
+  // the BeginFrameSource.  OutputSurface should call this once after binding to
+  // the client and then call again with a null while detaching.
+  virtual void SetBeginFrameSource(BeginFrameSource* source) = 0;
+
   virtual void SetNeedsRedrawRect(const gfx::Rect& damage_rect) = 0;
   virtual void DidSwapBuffers() = 0;
   virtual void DidSwapBuffersComplete() = 0;
@@ -39,7 +46,7 @@ class CC_EXPORT OutputSurfaceClient {
   // valid for the lifetime of the OutputSurfaceClient or until unregisted --
   // use SetTreeActivationCallback(base::Closure()) to unregister it.
   virtual void SetTreeActivationCallback(const base::Closure& callback) = 0;
-  // This allows the output surface to ask it's client for a draw.
+  // This allows the output surface to ask its client for a draw.
   virtual void OnDraw(const gfx::Transform& transform,
                       const gfx::Rect& viewport,
                       const gfx::Rect& clip,