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

ash/system/locale/tray_locale.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_LOCALE_TRAY_LOCALE_H_
 #define ASH_SYSTEM_LOCALE_TRAY_LOCALE_H_
 
 #include <string>
 
 #include "ash/system/locale/locale_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
 namespace internal {
 
 namespace tray {
 class LocaleNotificationView;
 }
 
 class TrayLocale : public SystemTrayItem,
                    public LocaleObserver {
  public:
-  TrayLocale();
+  explicit TrayLocale(SystemTray* system_tray);
   virtual ~TrayLocale();
 
  private:
   // Overridden from TrayImageItem.
   virtual views::View* CreateNotificationView(
       user::LoginStatus status) OVERRIDE;
   virtual void DestroyNotificationView() OVERRIDE;
 
   // Overridden from LocaleObserver.
   virtual void OnLocaleChanged(LocaleObserver::Delegate* delegate,
                                const std::string& cur_locale,
                                const std::string& from_locale,
                                const std::string& to_locale) OVERRIDE;
 
   tray::LocaleNotificationView* notification_;
   LocaleObserver::Delegate* delegate_;
   std::string cur_locale_;
   std::string from_locale_;
   std::string to_locale_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayLocale);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_LOCALE_TRAY_LOCALE_H_