Add PluginMessageLoopProxy and use it for Host plugin UI thread.

remoting/host/host_mock_objects.h

 // Copyright (c) 2011 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_HOST_HOST_MOCK_OBJECTS_H_
 #define REMOTING_HOST_HOST_MOCK_OBJECTS_H_
 
 #include "remoting/host/access_verifier.h"
 #include "remoting/host/capturer.h"
 #include "remoting/host/curtain.h"
@@ skipping 63 matching lines @@
 };
 
 class MockChromotingHostContext : public ChromotingHostContext {
  public:
   MockChromotingHostContext();
   virtual ~MockChromotingHostContext();
 
   MOCK_METHOD0(Start, void());
   MOCK_METHOD0(Stop, void());
   MOCK_METHOD0(jingle_thread, JingleThread*());
+  MOCK_METHOD0(ui_message_loop, base::MessageLoopProxy*());
   MOCK_METHOD0(main_message_loop, MessageLoop*());
   MOCK_METHOD0(encode_message_loop, MessageLoop*());
   MOCK_METHOD0(network_message_loop, base::MessageLoopProxy*());
-  MOCK_METHOD0(ui_message_loop, MessageLoop*());
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockChromotingHostContext);
 };
 
 class MockClientSessionEventHandler : public ClientSession::EventHandler {
  public:
   MockClientSessionEventHandler();
   virtual ~MockClientSessionEventHandler();
 
@@ skipping 40 matching lines @@
   MOCK_METHOD2(VerifyPermissions, bool(const std::string& client_jid,
                                        const std::string& token));
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockAccessVerifier);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_HOST_MOCK_OBJECTS_H_