Add chrome.screenlockPrivate API functions to handle alternate auth types.

chrome/test/data/extensions/api_test/screenlock_private/lock_unlock/test.js

 // Copyright 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.
 
 var stage = 0;
 
 function step() {
   chrome.screenlockPrivate.getLocked(function gotLocked(locked) {
     if (stage === 0) {
       if (locked) {
@@ skipping 23 matching lines @@
 
 chrome.screenlockPrivate.onChanged.addListener(function(locked) {
   if (locked != (1 == (stage % 2))) {
     chrome.test.fail((locked ? '' : 'un') + 'locked at stage ' + stage +
                      ' onChanged');
   } else {
     return step();
   }
 });
 
-step();
+chrome.test.runTests([
+    function testLockUnlock() {
+      step();
+    }
+]);