Allow cmdbuffer creation from compositor thread.

content/renderer/gpu/gpu_surface_proxy.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_GPU_GPU_SURFACE_PROXY_H_
 #define CONTENT_RENDERER_GPU_GPU_SURFACE_PROXY_H_
 #pragma once
 
 #if defined(ENABLE_GPU)
 
+#include "base/memory/weak_ptr.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_message.h"
 
 namespace gfx {
 class Size;
 }
 
 // Client side proxy that forwards messages to a GpuSurfaceStub.
-class GpuSurfaceProxy : public IPC::Channel::Listener {
+class GpuSurfaceProxy : public IPC::Channel::Listener,
+                        public base::SupportsWeakPtr<GpuSurfaceProxy> {
  public:
   GpuSurfaceProxy(IPC::Channel::Sender* channel, int route_id);
   virtual ~GpuSurfaceProxy();
 
   // IPC::Channel::Listener implementation:
   virtual bool OnMessageReceived(const IPC::Message& message);
   virtual void OnChannelError();
 
   int route_id() const { return route_id_; }
 
  private:
 
   // Send an IPC message over the GPU channel. This is private to fully
   // encapsulate the channel; all callers of this function must explicitly
   // verify that the channel is still available.
   bool Send(IPC::Message* msg);
 
   IPC::Channel::Sender* channel_;
   int route_id_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuSurfaceProxy);
 };
 
 #endif  // ENABLE_GPU
 
 #endif  // CONTENT_RENDERER_GPU_GPU_SURFACE_PROXY_H_