RefCounted types should not have public destructors, delegate cleanup

ipc/ipc_channel.h

 // Copyright (c) 2012 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_H_
 #define IPC_IPC_CHANNEL_H_
 #pragma once
 
 #include <string>
 
@@ skipping 22 matching lines @@
 // currently used by automation and service processes.
 
 class IPC_EXPORT Channel : public Message::Sender {
   // Security tests need access to the pipe handle.
   friend class ChannelTest;
 
  public:
   // Implemented by consumers of a Channel to receive messages.
   class IPC_EXPORT Listener {
    public:
-    virtual ~Listener() {}
-
     // Called when a message is received.  Returns true iff the message was
     // handled.
     virtual bool OnMessageReceived(const Message& message) = 0;
 
     // Called when the channel is connected and we have received the internal
     // Hello message from the peer.
     virtual void OnChannelConnected(int32 peer_pid) {}
 
     // Called when an error is detected that causes the channel to close.
     // This method is not called when a channel is closed normally.
     virtual void OnChannelError() {}
 
 #if defined(OS_POSIX)
     // Called on the server side when a channel that listens for connections
     // denies an attempt to connect.
     virtual void OnChannelDenied() {}
 
     // Called on the server side when a channel that listens for connections
     // has an error that causes the listening channel to close.
     virtual void OnChannelListenError() {}
 #endif  // OS_POSIX
+
+   protected:
+    virtual ~Listener() {}
   };
 
   // Flags to test modes
   enum ModeFlags {
     MODE_NO_FLAG = 0x0,
     MODE_SERVER_FLAG = 0x1,
     MODE_CLIENT_FLAG = 0x2,
     MODE_NAMED_FLAG = 0x4,
 #if defined(OS_POSIX)
     MODE_OPEN_ACCESS_FLAG = 0x8, // Don't restrict access based on client UID.
@@ skipping 146 matching lines @@
 
  private:
   // PIMPL to which all channel calls are delegated.
   class ChannelImpl;
   ChannelImpl *channel_impl_;
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_H_