Add missing IWYU message_loop.h includes.

content/browser/appcache/appcache_request_handler_unittest.cc

 // Copyright 2014 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 "content/browser/appcache/appcache_request_handler.h"
 
 #include <stdint.h>
 
 #include <stack>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "content/browser/appcache/appcache.h"
 #include "content/browser/appcache/appcache_backend_impl.h"
 #include "content/browser/appcache/appcache_url_request.h"
 #include "content/browser/appcache/appcache_url_request_job.h"
 #include "content/browser/appcache/mock_appcache_policy.h"
@@ skipping 1116 matching lines @@
 
 TEST_F(AppCacheRequestHandlerTest, WorkerRequest) {
   RunTestOnIOThread(&AppCacheRequestHandlerTest::WorkerRequest);
 }
 
 TEST_F(AppCacheRequestHandlerTest, MainResource_Blocked) {
   RunTestOnIOThread(&AppCacheRequestHandlerTest::MainResource_Blocked);
 }
 
 }  // namespace content