Check for warnings when loading extensions in browser tests.

chrome/test/data/extensions/api_test/webnavigation/test_crossProcess.js

 // Copyright (c) 2012 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.
 
-function runTests() {
+onload = function() {
   var getURL = chrome.extension.getURL;
   var URL_REGULAR =
       "http://127.0.0.1:PORT/files/extensions/api_test/webnavigation/crossProcess/empty.html";
   var URL_REDIRECT = "http://www.a.com:PORT/server-redirect";
   var URL_TEST = "http://127.0.0.1:PORT/test";
   chrome.tabs.create({"url": "about:blank"}, function(tab) {
     var tabId = tab.id;
     chrome.test.getConfig(function(config) {
       var fixPort = function(url) {
         return url.replace(/PORT/g, config.testServer.port);
@@ skipping 612 matching lines @@
                 "a-onHistoryStateUpdated"] ]);
 
           chrome.tabs.update(
               tabId,
               { url: getURL('crossProcess/i.html?' + config.testServer.port) });
         },
 
       ]);
     });
   });
-}
+};