Attempt four at landing the "histogram.h removed from message_loop.h" patch.

chrome/renderer/gpu_channel_host.h

 // Copyright (c) 2010 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 CHROME_RENDERER_GPU_CHANNEL_HOST_H_
 #define CHROME_RENDERER_GPU_CHANNEL_HOST_H_
 
 #include <string>
 
 #include "base/hash_tables.h"
+#include "base/scoped_ptr.h"
 #include "chrome/common/message_router.h"
 #include "gfx/native_widget_types.h"
 #include "gfx/size.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_sync_channel.h"
 
 class CommandBufferProxy;
 
 // Encapsulates an IPC channel between the renderer and one plugin process.
@@ skipping 55 matching lines @@
 
   // Keep track of all the registered CommandBufferProxies to
   // inform about OnChannelError
   typedef base::hash_map<int, IPC::Channel::Listener*> ProxyMap;
   ProxyMap proxies_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuChannelHost);
 };
 
 #endif  // CHROME_RENDERER_GPU_CHANNEL_HOST_H_