Allow cmdbuffer creation from compositor thread.

content/renderer/gpu/command_buffer_proxy.h

Index: content/renderer/gpu/command_buffer_proxy.h
diff --git a/content/renderer/gpu/command_buffer_proxy.h b/content/renderer/gpu/command_buffer_proxy.h
index 8c62508bb0194ef93837bfca99391cc8306f4ac7..91f69fe3f0a18d92cebf817fea7153810cb1b984 100644
--- a/content/renderer/gpu/command_buffer_proxy.h
+++ b/content/renderer/gpu/command_buffer_proxy.h
@@ -14,6 +14,7 @@
 #include "base/callback_old.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "content/renderer/gpu/gpu_video_decode_accelerator_host.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 #include "ipc/ipc_channel.h"
@@ -34,7 +35,8 @@ class Task;
 // Client side proxy that forwards messages synchronously to a
 // CommandBufferStub.
 class CommandBufferProxy : public gpu::CommandBuffer,
-                           public IPC::Channel::Listener {
+                           public IPC::Channel::Listener,
+                           public base::SupportsWeakPtr<CommandBufferProxy> {
  public:
   CommandBufferProxy(GpuChannelHost* channel, int route_id);
   virtual ~CommandBufferProxy();