Implement AutomationNode.querySelector().

chrome/test/data/extensions/api_test/automation/tests/tabs/common.js

 // Copyright 2014 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 assertEq = chrome.test.assertEq;
 var assertFalse = chrome.test.assertFalse;
 var assertTrue = chrome.test.assertTrue;
 
 var EventType = chrome.automation.EventType;
 var RoleType = chrome.automation.RoleType;
 var StateType = chrome.automation.StateType;
 
 var rootNode = null;
 
 function createTab(url, callback) {
   chrome.tabs.create({"url": url}, function(tab) {
     callback(tab);
   });
 }
 
-function setUpAndRunTests(allTests) {
-  getUrlFromConfig(function(url) {
+function setUpAndRunTests(allTests, opt_path) {
+  var path = opt_path || 'index.html';
+  getUrlFromConfig(path, function(url) {
     createTab(url, function(unused_tab) {
       chrome.automation.getTree(function (returnedRootNode) {
         rootNode = returnedRootNode;
         if (rootNode.attributes.docLoaded) {
           chrome.test.runTests(allTests);
           return;
         }
         rootNode.addEventListener('loadComplete', function() {
           chrome.test.runTests(allTests);
         });
       });
     });
   });
 }
 
-function getUrlFromConfig(callback) {
+function getUrlFromConfig(path, callback) {
   chrome.test.getConfig(function(config) {
     assertTrue('testServer' in config, 'Expected testServer in config');
-    var url = 'http://a.com:PORT/index.html'
+    var url = ('http://a.com:PORT/' + path)
         .replace(/PORT/, config.testServer.port);
     callback(url)
   });
 }