Add PluginMessageLoopProxy and use it for Host plugin UI thread.

remoting/protocol/protocol_test_client.cc

Index: remoting/protocol/protocol_test_client.cc
diff --git a/remoting/protocol/protocol_test_client.cc b/remoting/protocol/protocol_test_client.cc
index b9d8d0ae43c0cba4d40846c44d2dbe5fecf08714..faf13724e0e9f8878be9dc26744c14b95ecf8e27 100644
--- a/remoting/protocol/protocol_test_client.cc
+++ b/remoting/protocol/protocol_test_client.cc
@@ -17,6 +17,7 @@ extern "C" {
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/message_loop_proxy.h"
+#include "base/synchronization/waitable_event.h"
 #include "base/test/mock_chrome_application_mac.h"
 #include "base/time.h"
 #include "crypto/nss_util.h"
@@ -33,8 +34,17 @@ namespace remoting {
 namespace protocol {
 
 namespace {
+
 const int kBufferSize = 4096;
 const char kDummyAuthToken[] = "";
+
+void InitializeMessageLoopProxy(
+    scoped_refptr<base::MessageLoopProxy>* proxy,
+    base::WaitableEvent* done) {
+  *proxy = base::MessageLoopProxy::CreateForCurrentThread();
+  done->Signal();
+}
+
 }  // namespace
 
 class ProtocolTestClient;
@@ -219,12 +229,18 @@ void ProtocolTestClient::Run(const std::string& username,
   remoting::JingleThread jingle_thread;
   jingle_thread.Start();
 
+  scoped_refptr<base::MessageLoopProxy> network_message_loop;
+  base::WaitableEvent proxy_event(true, false);
+  jingle_thread.message_loop()->PostTask(FROM_HERE, base::Bind(
+      &InitializeMessageLoopProxy, &network_message_loop, &proxy_event));
+  proxy_event.Wait();
+
   signal_strategy_.reset(
       new XmppSignalStrategy(&jingle_thread, username, auth_token,
                              auth_service));
   signal_strategy_->Init(this);
-  session_manager_.reset(JingleSessionManager::CreateNotSandboxed(
-      jingle_thread.message_loop_proxy()));
+  session_manager_.reset(
+      JingleSessionManager::CreateNotSandboxed(network_message_loop));
 
   host_jid_ = host_jid;