Remove ash tray utility functions that are no-ops in MD.

ash/common/system/chromeos/power/tray_power.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_COMMON_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_
 
 #include <memory>
 
 #include "ash/common/system/chromeos/power/power_status.h"
@@ skipping 55 matching lines @@
     USB_CHARGER,
     UNCONFIRMED_SPRING_CHARGER,
     SAFE_SPRING_CHARGER,
     CHARGER_TYPE_COUNT,
   };
 
   // Overridden from SystemTrayItem.
   views::View* CreateTrayView(LoginStatus status) override;
   views::View* CreateDefaultView(LoginStatus status) override;
   void DestroyTrayView() override;
-  void DestroyDefaultView() override;
-  void UpdateAfterLoginStatusChange(LoginStatus status) override;
-  void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) override;
 
   // Overridden from PowerStatus::Observer.
   void OnPowerStatusChanged() override;
 
   // Shows a notification that a low-power USB charger has been connected.
   // Returns true if a notification was shown or explicitly hidden.
   bool MaybeShowUsbChargerNotification();
 
   // Shows a notification when dual-role devices are connected.
   void MaybeShowDualRoleNotification();
@@ skipping 19 matching lines @@
   // Has the user already dismissed a low-power notification? Should be set
   // back to false when all power sources are disconnected.
   bool usb_notification_dismissed_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayPower);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_POWER_TRAY_POWER_H_