Add a ChannelEndpointClient abstraction.

mojo/edk/system/proxy_message_pipe_endpoint.cc

 // Copyright 2013 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.
 
 #include "mojo/edk/system/proxy_message_pipe_endpoint.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "mojo/edk/system/channel_endpoint.h"
@@ skipping 30 matching lines @@
   LOG_IF(WARNING, !channel_endpoint_->EnqueueMessage(message.Pass()))
       << "Failed to write enqueue message to channel";
 }
 
 void ProxyMessagePipeEndpoint::Close() {
   DetachIfNecessary();
 }
 
 void ProxyMessagePipeEndpoint::DetachIfNecessary() {
   if (channel_endpoint_.get()) {
-    channel_endpoint_->DetachFromMessagePipe();
+    channel_endpoint_->DetachFromClient();
     channel_endpoint_ = nullptr;
   }
 }
 
 }  // namespace system
 }  // namespace mojo