Update references to the extension messaging APIs to point to the "runtime"

chrome/test/data/extensions/api_test/content_scripts/bypass_page_csp/background.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.
 
-chrome.extension.onConnect.addListener(function(port) {
+chrome.runtime.onConnect.addListener(function(port) {
   chrome.test.log("got connect");
   port.onMessage.addListener(function(msg) {
     chrome.test.log("got message: " + msg);
     if (msg)
       chrome.test.notifyPass();
     else
       chrome.test.notifyFail();
   });
 });
 
 chrome.test.getConfig(function(config) {
   chrome.test.log("Creating tab...");
 
   var test_url =
       "http://localhost:PORT/files/extensions/test_file_with_csp.html"
           .replace(/PORT/, config.testServer.port);
 
   chrome.tabs.create({ url: test_url });
 });