Remove Nested Message Loop from MenuController

ui/views/controls/menu/menu_message_loop_mac.h

-// 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.
-
-#ifndef UI_VIEWS_CONTROLS_MENU_MENU_MESSAGE_LOOP_MAC_H_
-#define UI_VIEWS_CONTROLS_MENU_MENU_MESSAGE_LOOP_MAC_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "ui/views/controls/menu/menu_message_loop.h"
-
-namespace base {
-class RunLoop;
-}
-
-namespace views {
-
-class MenuMessageLoopMac : public MenuMessageLoop {
- public:
-  MenuMessageLoopMac();
-  ~MenuMessageLoopMac() override;
-
-  // MenuMessageLoop:
-  void Run() override;
-  void QuitNow() override;
-
- private:
-  base::RunLoop* run_loop_ = nullptr;
-
-  DISALLOW_COPY_AND_ASSIGN(MenuMessageLoopMac);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_CONTROLS_MENU_MENU_MESSAGE_LOOP_MAC_H_