Add device policy to disallow shutdown - ash UI modifications

ash/system/date/date_default_view.h

Index: ash/system/date/date_default_view.h
diff --git a/ash/system/date/date_default_view.h b/ash/system/date/date_default_view.h
index 0a7d43d883d70ccd7435b607fbd9844e27afac7d..6356bd4569abc8a26f301016ed33166a0f202852 100644
--- a/ash/system/date/date_default_view.h
+++ b/ash/system/date/date_default_view.h
@@ -6,8 +6,10 @@
 #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"
 
@@ -19,26 +21,35 @@ class DateView;
 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* GetShutdownButtonView();
+  views::View* GetRebootButtonView();
   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* reboot_;
   TrayPopupHeaderButton* shutdown_;
   TrayPopupHeaderButton* lock_;
   tray::DateView* date_view_;
 
+  base::WeakPtrFactory<DateDefaultView> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DateDefaultView);
 };