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

ash/system/chromeos/network/tray_network.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_CHROMEOS_NETWORK_TRAY_NETWORK_H
 #define ASH_SYSTEM_CHROMEOS_NETWORK_TRAY_NETWORK_H
 
 #include "ash/system/chromeos/network/network_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 11 matching lines @@
 }
 
 class TrayNetwork : public SystemTrayItem,
                     public NetworkObserver {
  public:
   enum DetailedViewType {
     LIST_VIEW,
     WIFI_VIEW,
   };
 
-  TrayNetwork();
+  explicit TrayNetwork(SystemTray* system_tray);
   virtual ~TrayNetwork();
 
   // 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 views::View* CreateNotificationView(
       user::LoginStatus status) OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
@@ skipping 29 matching lines @@
   scoped_ptr<tray::NetworkMessages> messages_;
   bool request_wifi_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayNetwork);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_NETWORK_TRAY_NETWORK_H