Move mus to //services/ui

components/mus/ws/user_id_tracker_observer.h

-// Copyright 2016 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 COMPONENTS_MUS_WS_USER_ID_TRACKER_OBSERVER_H_
-#define COMPONENTS_MUS_WS_USER_ID_TRACKER_OBSERVER_H_
-
-#include <stdint.h>
-
-#include "components/mus/ws/user_id.h"
-
-namespace mus {
-namespace ws {
-
-class UserIdTrackerObserver {
- public:
-  virtual void OnActiveUserIdChanged(const UserId& previously_active_id,
-                                     const UserId& active_id) {}
-  virtual void OnUserIdAdded(const UserId& id) {}
-  virtual void OnUserIdRemoved(const UserId& id) {}
-
- protected:
-  virtual ~UserIdTrackerObserver() {}
-};
-
-}  // namespace ws
-}  // namespace mus
-
-#endif  // COMPONENTS_MUS_WS_USER_ID_TRACKER_OBSERVER_H_