Revert of base: Remove use of MessageLoopProxy

base/test/thread_test_helper.cc

 // 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.
 
 #include "base/test/thread_test_helper.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/threading/thread_restrictions.h"
 
 namespace base {
 
 ThreadTestHelper::ThreadTestHelper(
-    scoped_refptr<SingleThreadTaskRunner> target_thread)
+    const scoped_refptr<MessageLoopProxy>& target_thread)
     : test_result_(false),
-      target_thread_(target_thread.Pass()),
+      target_thread_(target_thread),
       done_event_(false, false) {
 }
 
 bool ThreadTestHelper::Run() {
   if (!target_thread_->PostTask(
           FROM_HERE, base::Bind(&ThreadTestHelper::RunInThread, this))) {
     return false;
   }
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
   done_event_.Wait();
   return test_result_;
 }
 
 void ThreadTestHelper::RunTest() { set_test_result(true); }
 
 ThreadTestHelper::~ThreadTestHelper() {}
 
 void ThreadTestHelper::RunInThread() {
   RunTest();
   done_event_.Signal();
 }
 
 }  // namespace base