Add missing argument to Element.setAttribute() calls

native_client_sdk/src/examples/demo/drive/example.js

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 "use strict";
 
 var authToken = '';
 
 function getAuthToken(interactive) {
   chrome.identity.getAuthToken(
       {'interactive': interactive}, onGetAuthToken);
 }
 
 function onGetAuthToken(authToken) {
   var signInEl = document.getElementById('signIn');
   var getFileEl = document.getElementById('getFile');
   if (authToken) {
-    signInEl.setAttribute('hidden');
+    signInEl.setAttribute('hidden', '');
     getFileEl.removeAttribute('hidden');
     window.authToken =  authToken;
 
     // Send the auth token to the NaCl module.
     common.naclModule.postMessage('token:'+authToken);
   } else {
     // There is no auth token; this means that the user has yet to authorize
     // this app. Display a button to let the user sign in and authorize this
     // application.
     signInEl.removeAttribute('hidden');
-    getFileEl.setAttribute('hidden');
+    getFileEl.setAttribute('hidden', '');
   }
 };
 
 // Called by the common.js module.
 function moduleDidLoad() {
   // The module is not hidden by default so we can easily see if the plugin
   // failed to load.
   common.hideModule();
 
   // Make sure this example is running as a packaged app. If not, display a
@@ skipping 21 matching lines @@
     getAuthToken(true);
   });
 
   document.getElementById('getFile').addEventListener('click', function () {
     // Clear the file contents dialog box.
     document.getElementById('contents').textContent = '';
 
     common.naclModule.postMessage('getFile');
   });
 }