Add device policy to disallow shutdown - WebUI modifications

ash/system/date/date_default_view.cc

Index: ash/system/date/date_default_view.cc
diff --git a/ash/system/date/date_default_view.cc b/ash/system/date/date_default_view.cc
index aa86cc8f8d55163e3b1737df59a623224fa69cbd..ca64a1efa5352955cf799a32668a6e888eacb179 100644
--- a/ash/system/date/date_default_view.cc
+++ b/ash/system/date/date_default_view.cc
@@ -102,6 +102,10 @@ views::View* DateDefaultView::GetHelpButtonView() {
   return help_button_;
 }
 
+const views::View* DateDefaultView::GetShutdownButtonViewForTest() const {
+  return shutdown_button_;
+}
+
 tray::DateView* DateDefaultView::GetDateView() {
   return date_view_;
 }