Add PluginMessageLoopProxy and use it for Host plugin UI thread.

remoting/client/client_context.h

 // Copyright (c) 2010 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 REMOTING_CLIENT_CLIENT_CONTEXT_H_
 #define REMOTING_CLIENT_CLIENT_CONTEXT_H_
 
 #include <string>
 
 #include "base/message_loop_proxy.h"
@@ skipping 22 matching lines @@
 
   // A thread that handles all decode operations.
   base::Thread decode_thread_;
 
   // A thread that handles all network IO.
   //
   // TODO(sergeyu): Remove |network_thread_| and use main plugin
   // message loop for network IO.
   base::Thread network_thread_;
 
+  scoped_refptr<base::MessageLoopProxy> network_message_loop_;
+
   DISALLOW_COPY_AND_ASSIGN(ClientContext);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_CLIENT_CLIENT_CONTEXT_H_