It is time.

ui/wm/core/user_activity_observer.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_WM_CORE_USER_ACTIVITY_OBSERVER_H_
-#define UI_WM_CORE_USER_ACTIVITY_OBSERVER_H_
-
-#include "base/basictypes.h"
-#include "ui/wm/wm_export.h"
-
-namespace ui {
-class Event;
-}
-
-namespace wm {
-
-// Interface for classes that want to be notified about user activity.
-// Implementations should register themselves with UserActivityDetector.
-class WM_EXPORT UserActivityObserver {
- public:
-  // Invoked periodically while the user is active (i.e. generating input
-  // events). |event| is the event that triggered the notification; it may
-  // be NULL in some cases (e.g. testing or synthetic invocations).
-  virtual void OnUserActivity(const ui::Event* event) = 0;
-
- protected:
-  UserActivityObserver() {}
-  virtual ~UserActivityObserver() {}
-
-  DISALLOW_COPY_AND_ASSIGN(UserActivityObserver);
-};
-
-}  // namespace wm
-
-#endif  // UI_WM_CORE_USER_ACTIVITY_OBSERVER_H_