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

ash/system/tray/tray_empty.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/tray/tray_empty.h"
 
 #include "ui/views/layout/box_layout.h"
 #include "ui/views/background.h"
 #include "ui/views/view.h"
 
@@ skipping 17 matching lines @@
 namespace internal {
 
 TrayEmpty::TrayEmpty() {}
 
 TrayEmpty::~TrayEmpty() {}
 
 views::View* TrayEmpty::CreateTrayView(user::LoginStatus status) {
   return NULL;
 }
 
-views::View* TrayEmpty::CreateDefaultView(user::LoginStatus status) {
+views::View* TrayEmpty::CreateDefaultView(user::LoginStatus status,
+                                          int bubble_width) {
   if (status == user::LOGGED_IN_NONE)
     return NULL;
 
   views::View* view = new views::View;
   view->set_background(new EmptyBackground());
   view->set_border(views::Border::CreateEmptyBorder(10, 0, 0, 0));
   view->SetLayoutManager(new views::BoxLayout(views::BoxLayout::kVertical,
         0, 0, 0));
   view->SetPaintToLayer(true);
   view->SetFillsBoundsOpaquely(false);
   return view;
 }
 
 views::View* TrayEmpty::CreateDetailedView(user::LoginStatus status) {
   return NULL;
 }
 
 void TrayEmpty::DestroyTrayView() {}
 
 void TrayEmpty::DestroyDefaultView() {}
 
 void TrayEmpty::DestroyDetailedView() {}
 
 void TrayEmpty::UpdateAfterLoginStatusChange(user::LoginStatus status) {}
 
 }  // namespace internal
 }  // namespace ash