Add flow control between renderer and GPU processes, and, on Mac OS X,...

chrome/gpu/gpu_command_buffer_stub.h

Index: chrome/gpu/gpu_command_buffer_stub.h
===================================================================
--- chrome/gpu/gpu_command_buffer_stub.h	(revision 67289)
+++ chrome/gpu/gpu_command_buffer_stub.h	(working copy)
@@ -51,6 +51,11 @@
 
   int32 route_id() const { return route_id_; }
 
+#if defined(OS_MACOSX)
+  // Called only by the GpuChannel.
+  void AcceleratedSurfaceBuffersSwapped(uint64 swap_buffers_count);
+#endif
+
  private:
   // Message handlers:
   void OnInitialize(int32 size, base::SharedMemoryHandle* ring_buffer);