mash: Migrate locale observer and notification to common.

ash/system/locale/locale_notification_controller.h

-// Copyright 2013 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 ASH_SYSTEM_LOCALE_LOCALE_NOTIFICATION_CONTROLLER_H_
-#define ASH_SYSTEM_LOCALE_LOCALE_NOTIFICATION_CONTROLLER_H_
-
-#include <string>
-
-#include "ash/system/locale/locale_observer.h"
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-
-namespace ash {
-
-// Observes the locale change and creates rich notification for the change.
-class LocaleNotificationController : public LocaleObserver {
- public:
-  LocaleNotificationController();
-  ~LocaleNotificationController() override;
-
- private:
-  // Overridden from LocaleObserver.
-  void OnLocaleChanged(LocaleObserver::Delegate* delegate,
-                       const std::string& cur_locale,
-                       const std::string& from_locale,
-                       const std::string& to_locale) override;
-
-  std::string cur_locale_;
-  std::string from_locale_;
-  std::string to_locale_;
-
-  DISALLOW_COPY_AND_ASSIGN(LocaleNotificationController);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_LOCALE_LOCALE_NOTIFICATION_CONTROLLER_H_