Send vsync timebase updates to the browser compositor

content/common/gpu/image_transport_surface.h

Index: content/common/gpu/image_transport_surface.h
diff --git a/content/common/gpu/image_transport_surface.h b/content/common/gpu/image_transport_surface.h
index 391f72a361527156c666fe1e572daea5f9c121a2..7b6d1df4ce6b404de4fde33035beb8a756a23ed1 100644
--- a/content/common/gpu/image_transport_surface.h
+++ b/content/common/gpu/image_transport_surface.h
@@ -114,6 +114,8 @@ class ImageTransportHelper : public IPC::Listener {
   void SendAcceleratedSurfaceRelease(
       GpuHostMsg_AcceleratedSurfaceRelease_Params params);
   void SendResizeView(const gfx::Size& size);
+  void SendUpdateVSyncParameters(
+      base::TimeTicks timebase, base::TimeDelta interval);
 
   // Whether or not we should execute more commands.
   void SetScheduled(bool is_scheduled);
@@ -186,6 +188,10 @@ class PassThroughImageTransportSurface
  protected:
   virtual ~PassThroughImageTransportSurface();
 
+  // If updated vsync parameters can be determined, send this information to
+  // the browser.
+  virtual void SendVSyncUpdateIfAvailable();
+
  private:
   scoped_ptr<ImageTransportHelper> helper_;
   gfx::Size new_size_;