Send vsync timebase updates to the browser compositor

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index c5dc3ba076a19d948fe0e2a811291ea65d0cd9d9..71ddecbcdf2eaca6d50f81c41d864ce7fa78ba7d 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -54,6 +54,12 @@ class COMPOSITOR_EXPORT ContextFactory {
   virtual WebKit::WebGraphicsContext3D* CreateContext(
       Compositor* compositor) = 0;
 
+  // Creates an output surface for the given compositor. The factory may keep
+  // per-compositor data (e.g. a shared context), that needs to be cleaned up
+  // by calling RemoveCompositor when the compositor gets destroyed.
+  virtual WebKit::WebCompositorOutputSurface* CreateOutputSurface(
+      Compositor* compositor) = 0;
+
   // Creates a context used for offscreen rendering. This context can be shared
   // with all compositors.
   virtual WebKit::WebGraphicsContext3D* CreateOffscreenContext() = 0;
@@ -71,6 +77,8 @@ class COMPOSITOR_EXPORT DefaultContextFactory : public ContextFactory {
   // ContextFactory implementation
   virtual WebKit::WebGraphicsContext3D* CreateContext(
       Compositor* compositor) OVERRIDE;
+  virtual WebKit::WebCompositorOutputSurface* CreateOutputSurface(
+      Compositor* compositor) OVERRIDE;
   virtual WebKit::WebGraphicsContext3D* CreateOffscreenContext() OVERRIDE;
   virtual void RemoveCompositor(Compositor* compositor) OVERRIDE;