chromeos: Move SystemTrayDelegate::RequestShutdown to WmShell

ash/common/system/tiles/tiles_default_view.cc

 // Copyright 2016 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/common/system/tiles/tiles_default_view.h"
 
 #include "ash/common/metrics/user_metrics_action.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/system_menu_button.h"
 #include "ash/common/system/tray/system_tray.h"
@@ skipping 117 matching lines @@
     shell->system_tray_controller()->ShowHelp();
   } else if (sender == lock_button_) {
     shell->RecordUserMetricsAction(UMA_TRAY_LOCK_SCREEN);
 #if defined(OS_CHROMEOS)
     chromeos::DBusThreadManager::Get()
         ->GetSessionManagerClient()
         ->RequestLockScreen();
 #endif
   } else if (sender == power_button_) {
     shell->RecordUserMetricsAction(UMA_TRAY_SHUT_DOWN);
-    shell->system_tray_delegate()->RequestShutdown();
+    shell->RequestShutdown();
   }
 
   owner_->system_tray()->CloseSystemBubble();
 }
 
 void TilesDefaultView::OnShutdownPolicyChanged(bool reboot_on_shutdown) {
   if (!power_button_)
     return;
 
   power_button_->SetTooltipText(l10n_util::GetStringUTF16(
       reboot_on_shutdown ? IDS_ASH_STATUS_TRAY_REBOOT
                          : IDS_ASH_STATUS_TRAY_SHUTDOWN));
 }
 
 views::View* TilesDefaultView::GetHelpButtonView() const {
   return help_button_;
 }
 
 const views::CustomButton* TilesDefaultView::GetShutdownButtonViewForTest()
     const {
   return power_button_;
 }
 
 }  // namespace ash