Delete Tracked, and move Location to its own file.

base/message_loop_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 BASE_MESSAGE_LOOP_PROXY_H_
 #define BASE_MESSAGE_LOOP_PROXY_H_
 #pragma once
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/task.h"
 
+namespace tracked_objects {
+class Location;
+} // namespace tracked_objects
+
 namespace base {
 
 struct MessageLoopProxyTraits;
 
 // 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()
@@ skipping 119 matching lines @@
 
 struct MessageLoopProxyTraits {
   static void Destruct(const MessageLoopProxy* proxy) {
     proxy->OnDestruct();
   }
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_PROXY_H_