ipc: Make sure that ChannelReader is destroyed correctly.

ipc/ipc_channel_reader.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_READER_H_
 #define IPC_IPC_CHANNEL_READER_H_
 
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 57 matching lines @@
 
   // Returns true if the given message is an Hello message
   // sent on channel set-up.
   bool IsHelloMessage(const Message& m);
 
  protected:
   enum ReadState { READ_SUCCEEDED, READ_FAILED, READ_PENDING };
 
   Listener* listener() const { return listener_; }
 
+  // Subclasses should call this method in their destructor to give this class a
+  // chance to clean up state that might be dependent on subclass members.
+  void CleanUp();
+
   // Populates the given buffer with data from the pipe.
   //
   // Returns the state of the read. On READ_SUCCESS, the number of bytes
   // read will be placed into |*bytes_read| (which can be less than the
   // buffer size). On READ_FAILED, the channel will be closed.
   //
   // If the return value is READ_PENDING, it means that there was no data
   // ready for reading. The implementation is then responsible for either
   // calling AsyncReadComplete with the number of bytes read into the
   // buffer, or ProcessIncomingMessages to try the read again (depending
@@ skipping 83 matching lines @@
   // set contains the AttachmentIds that are needed to unblock the message.
   AttachmentIdSet blocked_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(ChannelReader);
 };
 
 }  // namespace internal
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_READER_H_