mash: Convert system tray logout button to wm common types

ash/system/chromeos/session/last_window_closed_logout_reminder.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 ASH_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_LOGOUT_REMINDER_H_
-#define ASH_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_LOGOUT_REMINDER_H_
-
-#include "ash/common/system/chromeos/session/last_window_closed_observer.h"
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-
-namespace ash {
-
-// Shows a dialog asking the user whether to end the session when the last
-// window has been closed in a public session.
-class LastWindowClosedLogoutReminder : public LastWindowClosedObserver {
- public:
-  LastWindowClosedLogoutReminder();
-  ~LastWindowClosedLogoutReminder() override;
-
-  void OnLastWindowClosed() override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(LastWindowClosedLogoutReminder);
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_LOGOUT_REMINDER_H_