Hook up system clock update dbus signal to chrome and ash tray ui.

ash/system/date/tray_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_DATE_TRAY_DATE_H_
 #define ASH_SYSTEM_DATE_TRAY_DATE_H_
 
 #include "ash/system/date/clock_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 
@@ skipping 25 matching lines @@
   virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
   virtual void DestroyDetailedView() OVERRIDE;
   virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) OVERRIDE;
   virtual void UpdateAfterShelfAlignmentChange(
       ShelfAlignment alignment) OVERRIDE;
 
   // Overridden from ClockObserver.
   virtual void OnDateFormatChanged() OVERRIDE;
+  virtual void OnSystemClockTimeUpdated() OVERRIDE;
   virtual void Refresh() OVERRIDE;
 
   void SetupLabelForTimeTray(views::Label* label);
 
   tray::TimeView* time_tray_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayDate);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_DATE_TRAY_DATE_H_