diff --git a/externs.js b/externs.js
index 3e45adfe7c..c7138f931c 100644
--- a/externs.js
+++ b/externs.js
@@ -40,3 +40,10 @@ dummy.getFileHandle = function() {};
 dummy.removeEntry = function() {};
 dummy.getFile = function() {};
 dummy.text = function() {};
+dummy.requestPermission = function() {};
+dummy.queryPermission = function() {};
+dummy.verifyPermission = function() {};
+dummy.createWritable = function() {};
+dummy.write = function() {};
+dummy.close = function() {};
+dummy.values = function() {};