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

ipc/ipc_channel_proxy.h

 // Copyright (c) 2006-2008 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 IPC_IPC_CHANNEL_PROXY_H__
 #define IPC_IPC_CHANNEL_PROXY_H__
 #pragma once
 
 #include <vector>
 
@@ skipping 69 matching lines @@
     // OnFilterRemoved is called immediately after this.
     virtual void OnChannelClosing();
 
     // Return true to indicate that the message was handled, or false to let
     // the message be handled in the default way.
     virtual bool OnMessageReceived(const Message& message);
 
     // Called when the message filter is about to be deleted.  This gives
     // derived classes the option of controlling which thread they're deleted
     // on etc.
-    virtual void OnDestruct();
+    virtual void OnDestruct() const;
   };
 
   struct MessageFilterTraits {
-    static void Destruct(MessageFilter* filter) {
+    static void Destruct(const MessageFilter* filter) {
       filter->OnDestruct();
     }
   };
 
   // Initializes a channel proxy.  The channel_id and mode parameters are
   // passed directly to the underlying IPC::Channel.  The listener is called on
   // the thread that creates the ChannelProxy.  The filter's OnMessageReceived
   // method is called on the thread where the IPC::Channel is running.  The
   // filter may be null if the consumer is not interested in handling messages
   // on the background thread.  Any message not handled by the filter will be
@@ skipping 120 matching lines @@
 
   // By maintaining this indirection (ref-counted) to our internal state, we
   // can safely be destroyed while the background thread continues to do stuff
   // that involves this data.
   scoped_refptr<Context> context_;
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_PROXY_H__