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

ash/system/chromeos/network/network_detailed_view.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_NETWORK_DETAILED_VIEW_H
 #define ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_DETAILED_VIEW_H
 
 #include "ash/system/tray/tray_details_view.h"
 
 namespace ash {
+
+class SystemTrayItem;
+
 namespace internal {
 
 namespace tray {
 
 // Abstract base class for all NetworkDetailedView derived subclasses,
 // which includes NetworkWifiDetailedView and NetworkListDetailedViewBase.
 class NetworkDetailedView : public TrayDetailsView {
  public:
+  explicit NetworkDetailedView(SystemTrayItem* tray) : TrayDetailsView(tray) {}
+
   enum DetailedViewType {
     LIST_VIEW,
     WIFI_VIEW,
   };
 
   virtual void Init() = 0;
   virtual DetailedViewType GetViewType() const = 0;
   // Updates network data and UI of the detailed view.
   virtual void Update() = 0;
 
  protected:
   virtual ~NetworkDetailedView() {}
 };
 
 }  // namespace tray
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_DETAILED_VIEW_H