Add PluginMessageLoopProxy and use it for Host plugin UI thread.

remoting/jingle_glue/jingle_thread.cc

Index: remoting/jingle_glue/jingle_thread.cc
diff --git a/remoting/jingle_glue/jingle_thread.cc b/remoting/jingle_glue/jingle_thread.cc
index 2dc37ada5001610a52a19a1282323bb90bb96c0a..b0b409a53d9636471f807b7d2bbe8a1e9c89ff89 100644
--- a/remoting/jingle_glue/jingle_thread.cc
+++ b/remoting/jingle_glue/jingle_thread.cc
@@ -6,7 +6,6 @@
 
 #include "base/basictypes.h"
 #include "base/logging.h"
-#include "base/message_loop_proxy.h"
 #include "base/message_pump.h"
 #include "base/time.h"
 #include "third_party/libjingle/source/talk/base/ssladapter.h"
@@ -154,7 +153,6 @@ void JingleThread::Start() {
 void JingleThread::Run() {
   JingleThreadMessageLoop message_loop(this);
   message_loop_ = &message_loop;
-  message_loop_proxy_ = base::MessageLoopProxy::CreateForCurrentThread();
 
   TaskPump task_pump;
   task_pump_ = &task_pump;
@@ -182,10 +180,6 @@ MessageLoop* JingleThread::message_loop() {
   return message_loop_;
 }
 
-base::MessageLoopProxy* JingleThread::message_loop_proxy() {
-  return message_loop_proxy_;
-}
-
 TaskPump* JingleThread::task_pump() {
   return task_pump_;
 }