Create a new base/message_loop directory and move the message_loop_proxy.

base/message_loop_proxy.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2013 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 BASE_MESSAGE_LOOP_PROXY_H_
-#define BASE_MESSAGE_LOOP_PROXY_H_
-
-#include "base/base_export.h"
-#include "base/compiler_specific.h"
-#include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
-
-namespace base {
-
-// This class provides a thread-safe refcounted interface to the Post* methods
-// of a message loop. This class can outlive the target message loop.
-// MessageLoopProxy objects are constructed automatically for all MessageLoops.
-// So, to access them, you can use any of the following:
-//   Thread::message_loop_proxy()
-//   MessageLoop::current()->message_loop_proxy()
-//   MessageLoopProxy::current()
-//
-// TODO(akalin): Now that we have the *TaskRunner interfaces, we can
-// merge this with MessageLoopProxyImpl.
-class BASE_EXPORT MessageLoopProxy : public SingleThreadTaskRunner {
- public:
-  // Gets the MessageLoopProxy for the current message loop, creating one if
-  // needed.
-  static scoped_refptr<MessageLoopProxy> current();
-
- protected:
-  MessageLoopProxy();
-  virtual ~MessageLoopProxy();
-};
-
-}  // namespace base
-
-#endif  // BASE_MESSAGE_LOOP_PROXY_H_
+// TODO(brettw) remove this forwarding file when all users reference the new
+// location.
+#include "base/message_loop/message_loop_proxy.h"