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

chrome/browser/chrome_browser_main.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 "chrome/browser/chrome_browser_main.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/process_info.h"
 #include "base/process_util.h"
+#include "base/run_loop.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/sys_string_conversions.h"
 #include "base/threading/platform_thread.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
@@ skipping 1861 matching lines @@
 bool ChromeBrowserMainParts::MainMessageLoopRun(int* result_code) {
   // Set the result code set in PreMainMessageLoopRun or set above.
   *result_code = result_code_;
   if (!run_message_loop_)
     return true;  // Don't run the default message loop.
 
   // This should be invoked as close to the start of the browser's
   // UI thread message loop as possible to get a stable measurement
   // across versions.
   RecordBrowserStartupTime();
-#if defined(USE_AURA)
-  MessageLoopForUI::current()->Run();
-#elif defined(TOOLKIT_VIEWS)
+  DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
+#if !defined(USE_AURA) && defined(TOOLKIT_VIEWS)
   views::AcceleratorHandler accelerator_handler;
-  MessageLoopForUI::current()->RunWithDispatcher(&accelerator_handler);
-#elif defined(USE_X11)
-  MessageLoopForUI::current()->RunWithDispatcher(NULL);
-#elif defined(OS_POSIX)
-  MessageLoopForUI::current()->Run();
+  base::RunLoop run_loop(&accelerator_handler);
+#else
+  base::RunLoop run_loop;
 #endif
+  run_loop.Run();
 
   return true;
 }
 
 void ChromeBrowserMainParts::PostMainMessageLoopRun() {
   // Start watching for jank during shutdown. It gets disarmed when
   // |shutdown_watcher_| object is destructed.
   shutdown_watcher_->Arm(base::TimeDelta::FromSeconds(300));
 
   // Disarm the startup hang detector time bomb if it is still Arm'ed.
@@ skipping 102 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead_";
     uma_name += pre_read_percentage;
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }