Remove message_loop_helpers.h and update the includes to point to the new location.

net/url_request/url_request_context_getter.h

 // Copyright (c) 2012 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 CHROME_COMMON_NET_URL_REQUEST_CONTEXT_GETTER_H_
 #define CHROME_COMMON_NET_URL_REQUEST_CONTEXT_GETTER_H_
 #pragma once
 
 #include "base/memory/ref_counted.h"
-#include "base/message_loop_helpers.h"
+#include "base/sequenced_task_runner_helpers.h"
 #include "net/base/net_export.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace net {
 class CookieStore;
 class URLRequestContext;
 
@@ skipping 29 matching lines @@
 
 struct URLRequestContextGetterTraits {
   static void Destruct(const URLRequestContextGetter* context_getter) {
     context_getter->OnDestruct();
   }
 };
 
 }  // namespace net
 
 #endif  // CHROME_COMMON_NET_URL_REQUEST_CONTEXT_GETTER_H_