Add device policy to disallow shutdown - ash UI modifications

ash/test/test_system_tray_delegate.cc

Index: ash/test/test_system_tray_delegate.cc
diff --git a/ash/test/test_system_tray_delegate.cc b/ash/test/test_system_tray_delegate.cc
index 60fb4b31e1fc4fc81fba6b930baad00985792c7b..67f17462b753c990ca2e5cb62283156918a28de9 100644
--- a/ash/test/test_system_tray_delegate.cc
+++ b/ash/test/test_system_tray_delegate.cc
@@ -94,6 +94,10 @@ bool TestSystemTrayDelegate::GetSessionLengthLimit(
   return session_length_limit_set_;
 }
 
+void TestSystemTrayDelegate::Restart() {
+  base::MessageLoop::current()->Quit();
+}
+
 void TestSystemTrayDelegate::ShutDown() {
   base::MessageLoop::current()->Quit();
 }