Allow closing root window, or pressing the power button to shutdown ash_shell, and chrome /w chrome…

ash/system/status_area_widget.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/status_area_widget.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "ash/shell_window_ids.h"
@@ skipping 97 matching lines @@
   }
 
   virtual bool IsCapsLockOn() const OVERRIDE {
     return caps_lock_enabled_;
   }
 
   virtual void SetCapsLockEnabled(bool enabled) OVERRIDE {
     caps_lock_enabled_ = enabled;
   }
 
-  virtual void ShutDown() OVERRIDE {}
+  virtual void ShutDown() OVERRIDE {
+    MessageLoop::current()->Quit();
+  }
 
   virtual void SignOut() OVERRIDE {
     MessageLoop::current()->Quit();
   }
 
   virtual void RequestLockScreen() OVERRIDE {}
 
   virtual void RequestRestart() OVERRIDE {}
 
   virtual void GetAvailableBluetoothDevices(
@@ skipping 245 matching lines @@
     return;
   login_status_ = login_status;
   if (system_tray_)
     system_tray_->UpdateAfterLoginStatusChange(login_status);
   if (web_notification_tray_)
     web_notification_tray_->UpdateAfterLoginStatusChange(login_status);
 }
 
 }  // namespace internal
 }  // namespace ash