Revert "Revert "Const-ify RefCountedThreadSafe::AddRef and Release.""

base/message_loop_proxy.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 BASE_MESSAGE_LOOP_PROXY_H_
 #define BASE_MESSAGE_LOOP_PROXY_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/ref_counted.h"
@@ skipping 46 matching lines @@
   static scoped_refptr<MessageLoopProxy> CreateForCurrentThread();
 
  protected:
   friend struct MessageLoopProxyTraits;
 
   MessageLoopProxy();
   virtual ~MessageLoopProxy();
 
   // Called when the proxy is about to be deleted. Subclasses can override this
   // to provide deletion on specific threads.
-  virtual void OnDestruct();
+  virtual void OnDestruct() const;
 };
 
 struct MessageLoopProxyTraits {
-  static void Destruct(MessageLoopProxy* proxy) {
+  static void Destruct(const MessageLoopProxy* proxy) {
     proxy->OnDestruct();
   }
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_PROXY_H_