Stop using shell::GetInstance()->system_tray() in system tray items

ash/system/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_SYSTEM_POWER_TRAY_POWER_H_
 #define ASH_SYSTEM_POWER_TRAY_POWER_H_
 
 #include "ash/system/power/power_status_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 
@@ skipping 32 matching lines @@
 
  private:
   enum NotificationState {
     NOTIFICATION_NONE,
     NOTIFICATION_LOW_POWER,
     NOTIFICATION_CRITICAL
   };
 
   // Overridden from SystemTrayItem.
   virtual views::View* CreateTrayView(user::LoginStatus status) OVERRIDE;
-  virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
+  virtual views::View* CreateDefaultView(user::LoginStatus status,
+                                         int bubble_width) OVERRIDE;
   virtual views::View* CreateNotificationView(
       user::LoginStatus status) OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
   virtual void DestroyNotificationView() OVERRIDE;
   virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) OVERRIDE;
   virtual void UpdateAfterShelfAlignmentChange(
       ShelfAlignment alignment) OVERRIDE;
 
   // Overridden from PowerStatusObserver.
   virtual void OnPowerStatusChanged(const PowerSupplyStatus& status) OVERRIDE;
 
   // Sets |notification_state_|. Returns true if a notification should be shown.
   bool UpdateNotificationState(const PowerSupplyStatus& status);
 
   tray::PowerTrayView* power_tray_;
   tray::PowerNotificationView* notification_view_;
   NotificationState notification_state_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayPower);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_POWER_TRAY_POWER_H_