diff --git a/externs.js b/externs.js
index d25d716350..ab5ca56eba 100644
--- a/externs.js
+++ b/externs.js
@@ -425,6 +425,7 @@ var TopLevel = {
     "setAutoCancel" : function () {},
     "setBackgroundColor" : function () {},
     "setBarStyle" : function () {},
+    "setBlankPreviewFlag" : function () {},
     "setCategory" : function () {},
     "setChannelId" : function () {},
     "setCurrentDapp" : function () {},