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

chrome/browser/ui/views/simple_message_box_views.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/ui/simple_message_box.h"
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop.h"
+#include "base/run_loop.h"
 #include "chrome/browser/browser_process.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/controls/message_box_view.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/window/dialog_delegate.h"
 
 #if defined(USE_AURA)
 #include "ui/aura/client/dispatcher_client.h"
@@ skipping 151 matching lines @@
   // Use the widget's window itself so that the message loop
   // exists when the dialog is closed by some other means than
   // |Cancel| or |Accept|.
   aura::Window* anchor = parent ?
       parent : dialog->GetWidget()->GetNativeWindow();
   aura::client::GetDispatcherClient(anchor->GetRootWindow())->
       RunWithDispatcher(dialog, anchor, true);
 #else
   {
     MessageLoop::ScopedNestableTaskAllower allow(MessageLoopForUI::current());
-    MessageLoopForUI::current()->RunWithDispatcher(dialog);
+    base::RunLoop run_loop(dialog);
+    run_loop.Run();
   }
 #endif
   return dialog->result();
 }
 
 }  // namespace browser