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

ash/system/chromeos/network/tray_vpn.cc

 // 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.
 
 #include "ash/system/chromeos/network/tray_vpn.h"
 
 #include "ash/shell.h"
 #include "ash/system/chromeos/network/network_list_detailed_view_base.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 110 matching lines @@
       detailed_(NULL) {
 }
 
 TrayVPN::~TrayVPN() {
 }
 
 views::View* TrayVPN::CreateTrayView(user::LoginStatus status) {
   return NULL;
 }
 
-views::View* TrayVPN::CreateDefaultView(user::LoginStatus status) {
+views::View* TrayVPN::CreateDefaultView(user::LoginStatus status,
+                                        int bubble_width) {
   CHECK(default_ == NULL);
   if (status == user::LOGGED_IN_NONE)
     return NULL;
 
   // Do not show VPN line in uber tray bubble if VPN is not configured.
   std::vector<NetworkIconInfo> list;
   Shell::GetInstance()->tray_delegate()->GetVirtualNetworks(&list);
   if (list.size() == 0)
     return NULL;
 
@@ skipping 47 matching lines @@
 }
 
 void TrayVPN::ClearNetworkMessage(MessageType message_type) {
 }
 
 void TrayVPN::OnWillToggleWifi() {
 }
 
 }  // namespace internal
 }  // namespace ash