Make SingleThreadProxy a SchedulerClient

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index e8b4489d5c163d208e8b86867b442fa9cd9fcedd..3d9f38291ca9c1cc53bebd017896a54d68f28b8b 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -142,7 +142,6 @@ class CONTENT_EXPORT RenderWidget
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
   // blink::WebWidgetClient
-  virtual void suppressCompositorScheduling(bool enable);
   virtual void willBeginCompositorFrame();
   virtual void didAutoResize(const blink::WebSize& new_size);
   virtual void initializeLayerTreeView();
@@ -173,6 +172,9 @@ class CONTENT_EXPORT RenderWidget
   // Begins the compositor's scheduler to start producing frames.
   void StartCompositor();
 
+  // Stop compositing.
+  void DestroyLayerTreeView();
+
   // Called when a plugin is moved.  These events are queued up and sent with
   // the next paint or scroll message to the host.
   void SchedulePluginMove(const WebPluginGeometry& move);
@@ -623,6 +625,9 @@ class CONTENT_EXPORT RenderWidget
   // be sent, except for a Close.
   bool closing_;
 
+  // True if it is known that the host is in the process of being shut down.
+  bool host_closing_;
+
   // Whether this RenderWidget is currently swapped out, such that the view is
   // being rendered by another process.  If all RenderWidgets in a process are
   // swapped out, the process can exit.