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

chrome/test/data/extensions/context_menus/incognito/test.js

 // Copyright (c) 2010 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 inIncognitoContext = chrome.extension.inIncognitoContext;
 var incognitoStr = inIncognitoContext ? "incognito" : "regular";
 
 function onclick(info) {
   chrome.test.sendMessage("onclick fired " + incognitoStr);
 }
 
 window.onload = function() {
   chrome.contextMenus.create({title: "item " + incognitoStr,
                               onclick: onclick}, function() {
-    if (!chrome.extension.lastError) {
+    if (!chrome.runtime.lastError) {
       chrome.test.sendMessage("created item " + incognitoStr);
     }
   });
 };