Simplify rate limiting since it's main thread shared context only

content/renderer/gpu/render_widget_compositor.h

Index: content/renderer/gpu/render_widget_compositor.h
diff --git a/content/renderer/gpu/render_widget_compositor.h b/content/renderer/gpu/render_widget_compositor.h
index 2316bb8c44dff0dcbfedb8ce12e7f4fe59e12c58..d3019ce6ff7a773084390e5486a5167db82fdcf0 100644
--- a/content/renderer/gpu/render_widget_compositor.h
+++ b/content/renderer/gpu/render_widget_compositor.h
@@ -126,6 +126,7 @@ class RenderWidgetCompositor : public WebKit::WebLayerTreeView,
   virtual void ScheduleComposite() OVERRIDE;
   virtual scoped_refptr<cc::ContextProvider>
       OffscreenContextProvider() OVERRIDE;
+  virtual void RateLimitSharedMainThreadContext() OVERRIDE;
 
  private:
   RenderWidgetCompositor(RenderWidget* widget, bool threaded);