ash: Take the 24h clock pref into consideration when showing the time.

ash/system/power/tray_power_date.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_TRAY_POWER_DATE_H_
 #define ASH_SYSTEM_POWER_TRAY_POWER_DATE_H_
 #pragma once
 
+#include "ash/system/power/date_format_observer.h"
 #include "ash/system/power/power_status_controller.h"
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
 namespace internal {
 
 namespace tray {
 class DateView;
 class PowerPopupView;
 class PowerTrayView;
 }
 
 class TrayPowerDate : public SystemTrayItem,
-                      public PowerStatusController {
+                      public PowerStatusController,
+                      public DateFormatObserver {
  public:
   TrayPowerDate();
   virtual ~TrayPowerDate();
 
  private:
   // Overridden from SystemTrayItem.
   virtual views::View* CreateTrayView(user::LoginStatus status) OVERRIDE;
   virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
   virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
   virtual void DestroyDetailedView() OVERRIDE;
 
   // Overridden from PowerStatusController.
   virtual void OnPowerStatusChanged(const PowerSupplyStatus& status) OVERRIDE;
 
+  // Overridden from DateFormatObserver.
+  virtual void OnDateFormatChanged() OVERRIDE;
+
   scoped_ptr<tray::DateView> date_;
   scoped_ptr<tray::DateView> date_tray_;
 
   scoped_ptr<tray::PowerPopupView> power_;
   scoped_ptr<tray::PowerTrayView> power_tray_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayPowerDate);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_POWER_TRAY_POWER_DATE_H_