Add MessagePipe interface. Use it in ChannelDispatcherBase.

remoting/protocol/host_video_dispatcher.cc

 // Copyright 2014 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 "remoting/protocol/host_video_dispatcher.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "net/socket/stream_socket.h"
 #include "remoting/base/constants.h"
 #include "remoting/proto/video.pb.h"
+#include "remoting/protocol/message_pipe.h"
 #include "remoting/protocol/message_serialization.h"
 #include "remoting/protocol/video_feedback_stub.h"
 
 namespace remoting {
 namespace protocol {
 
 HostVideoDispatcher::HostVideoDispatcher()
     : ChannelDispatcherBase(kVideoChannelName) {}
 HostVideoDispatcher::~HostVideoDispatcher() {}
 
 void HostVideoDispatcher::ProcessVideoPacket(scoped_ptr<VideoPacket> packet,
                                              const base::Closure& done) {
-  writer()->Write(SerializeAndFrameMessage(*packet), done);
+  message_pipe()->Send(packet.get(), done);
 }
 
 void HostVideoDispatcher::OnIncomingMessage(
     scoped_ptr<CompoundBuffer> message) {
   scoped_ptr<VideoAck> ack = ParseMessage<VideoAck>(message.get());
   if (!ack)
     return;
   if (video_feedback_stub_)
     video_feedback_stub_->ProcessVideoAck(std::move(ack));
 }
 
 }  // namespace protocol
 }  // namespace remoting