Add device policy to disallow shutdown - ash UI modifications

ash/system/date/date_default_view.h

 // Copyright 2014 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_DATE_DATE_DEFAULT_VIEW_H_
 #define ASH_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_
 
 #include "ash/ash_export.h"
+#include "ash/system/chromeos/shutdown_policy_observer.h"
 #include "ash/system/user/login_status.h"
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
 
 namespace ash {
 namespace tray {
 class DateView;
 }  // namespace tray
 
 class TrayPopupHeaderButton;
 
 class ASH_EXPORT DateDefaultView : public views::View,
-                                   public views::ButtonListener {
+                                   public views::ButtonListener,
+                                   public ash::ShutdownPolicyObserver {
  public:
   explicit DateDefaultView(ash::user::LoginStatus login);
 
   ~DateDefaultView() override;
 
   views::View* GetHelpButtonView();
 
   tray::DateView* GetDateView();
   const tray::DateView* GetDateView() const;
 
+  // ash::ShutdownPolicyObserver:
+  void OnShutdownPolicyChanged(bool reboot_on_shutdown) override;
+
  private:
   // Overridden from views::ButtonListener.
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
-  TrayPopupHeaderButton* help_;
-  TrayPopupHeaderButton* shutdown_;
-  TrayPopupHeaderButton* lock_;
+  TrayPopupHeaderButton* help_button_;
+  TrayPopupHeaderButton* shutdown_button_;
+  TrayPopupHeaderButton* lock_button_;
   tray::DateView* date_view_;
 
+  base::WeakPtrFactory<DateDefaultView> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DateDefaultView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_DATE_DATE_DEFAULT_VIEW_H_