ash uber tray: Add entry for power and date.

ash/system/power/power_status_controller.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_SYSTEM_POWER_POWER_STATUS_CONTROLLER_H_
+#define ASH_SYSTEM_POWER_POWER_STATUS_CONTROLLER_H_
+
+namespace ash {
+
+struct PowerSupplyStatus;
+
+class PowerStatusController {
+ public:
+  virtual ~PowerStatusController() {}
+
+  virtual void OnPowerStatusChanged(const PowerSupplyStatus& status) = 0;
+};
+
+};
+
+#endif  // ASH_SYSTEM_POWER_POWER_STATUS_CONTROLLER_H_