Separate out IPC::Message::Sender and channel::Listener into a separate class.

ipc/ipc_sender.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_SENDER_H_
+#define IPC_IPC_SENDER_H_
+
+#include "ipc/ipc_export.h"
+
+namespace IPC {
+
+class Message;
+
+class IPC_EXPORT Sender {
+ public:
+  virtual ~Sender() {}
+
+  // Sends the given IPC message.  The implementor takes ownership of the
+  // given Message regardless of whether or not this method succeeds.  This
+  // is done to make this method easier to use.  Returns true on success and
+  // false otherwise.
+  virtual bool Send(Message* msg) = 0;
+};
+
+}  // namespace IPC
+
+#endif  // IPC_IPC_SENDER_H_