chromeos: Notify power manager about user activity.

ash/wm/user_activity_observer.h

+// Copyright (c) 2012 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_WM_USER_ACTIVITY_OBSERVER_H_
+#define ASH_WM_USER_ACTIVITY_OBSERVER_H_
+#pragma once
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+
+namespace ash {
+
+// Interface for classes that want to be notified about user activity.
+// Implementations should register themselves with UserActivityDetector.
+class ASH_EXPORT UserActivityObserver {
+ public:
+  // Invoked periodically while the user is active (i.e. generating input
+  // events).
+  virtual void OnUserActivity() = 0;
+
+ protected:
+  UserActivityObserver() {}
+  virtual ~UserActivityObserver() {}
+
+  DISALLOW_COPY_AND_ASSIGN(UserActivityObserver);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_USER_ACTIVITY_OBSERVER_H_