Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

content/browser/browser_main_loop.cc

 // 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.
 
 #include "content/browser/browser_main_loop.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/hi_res_timer_manager.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/run_loop.h"
 #include "base/string_number_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/browser/download/download_file_manager.h"
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/gamepad/gamepad_service.h"
 #include "content/browser/gpu/browser_gpu_channel_host_factory.h"
 #include "content/browser/gpu/gpu_process_host.h"
 #include "content/browser/gpu/gpu_process_host_ui_shim.h"
 #include "content/browser/in_process_webkit/webkit_thread.h"
@@ skipping 602 matching lines @@
   config.dwICC = ICC_WIN95_CLASSES;
   if (!InitCommonControlsEx(&config))
     LOG_GETLASTERROR(FATAL);
 #endif
 
   if (parts_.get())
     parts_->ToolkitInitialized();
 }
 
 void BrowserMainLoop::MainMessageLoopRun() {
+#if defined(OS_ANDROID)
+  // Android's main message loop is the Java message loop.
+  NOTREACHED();
+#else
+  DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
   if (parameters_.ui_task)
     MessageLoopForUI::current()->PostTask(FROM_HERE, *parameters_.ui_task);
 
-#if defined(OS_MACOSX)
-  MessageLoopForUI::current()->Run();
-#elif defined(OS_ANDROID)
-  // Android's main message loop is the Java message loop.
-  NOTREACHED();
-#else
-  MessageLoopForUI::current()->RunWithDispatcher(NULL);
+  base::RunLoop run_loop;
+  run_loop.Run();
 #endif
 }
 
 }  // namespace content