Fix menu for 'disable extension'.

ui/message_center/views/message_view.cc

Index: ui/message_center/views/message_view.cc
diff --git a/ui/message_center/views/message_view.cc b/ui/message_center/views/message_view.cc
index 68d6f3135fc8141c97bcee0c6ce93402b796d431..07f87b1e60fd21222b97a7a3ee18104351497c1f 100644
--- a/ui/message_center/views/message_view.cc
+++ b/ui/message_center/views/message_view.cc
@@ -215,9 +215,10 @@ MenuModel::MenuModel(message_center::NotificationChangeObserver* observer,
       observer_(observer),
       notification_id_(notification_id) {
   // Add 'disable notifications' menu item.
-  if (!extension_id.empty()) {
+  if (!extension_id.empty() && !display_source.empty()) {
     AddItem(kToggleExtensionCommand,
-            l10n_util::GetStringUTF16(IDS_MESSAGE_CENTER_EXTENSIONS_DISABLE));
+            l10n_util::GetStringFUTF16(IDS_MESSAGE_CENTER_EXTENSIONS_DISABLE,
+                                       display_source));
   } else if (!display_source.empty()) {
     AddItem(kTogglePermissionCommand,
             l10n_util::GetStringFUTF16(IDS_MESSAGE_CENTER_SITE_DISABLE,