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

ui/views/controls/menu/menu_controller.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 "ui/views/controls/menu/menu_controller.h"
 
 #include "base/i18n/case_conversion.h"
 #include "base/i18n/rtl.h"
+#include "base/run_loop.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/dragdrop/drag_utils.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/events.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/controls/button/menu_button.h"
@@ skipping 306 matching lines @@
   message_loop_depth_++;
   DCHECK_LE(message_loop_depth_, 2);
 #if defined(USE_AURA)
   root_window_ = parent->GetNativeWindow()->GetRootWindow();
   aura::client::GetDispatcherClient(root_window_)->
       RunWithDispatcher(this, parent->GetNativeWindow(), true);
 #else
   {
     MessageLoopForUI* loop = MessageLoopForUI::current();
     MessageLoop::ScopedNestableTaskAllower allow(loop);
-    loop->RunWithDispatcher(this);
+    base::RunLoop run_loop(this);
+    run_loop.Run();
   }
 #endif
   message_loop_depth_--;
 
   if (ViewsDelegate::views_delegate)
     ViewsDelegate::views_delegate->ReleaseRef();
 
   // Close any open menus.
   SetSelection(NULL, SELECTION_UPDATE_IMMEDIATELY | SELECTION_EXIT);
 
@@ skipping 1772 matching lines @@
              (!pending_state_.item->HasSubmenu() ||
               !pending_state_.item->GetSubmenu()->IsShowing())) {
     // On exit if the user hasn't selected an item with a submenu, move the
     // selection back to the parent menu item.
     SetSelection(pending_state_.item->GetParentMenuItem(),
                  SELECTION_OPEN_SUBMENU);
   }
 }
 
 }  // namespace views