GTTF: convert some tests in chrome to use EmbeddedTestServer patch nr 1

chrome/test/data/extensions/api_test/app_background_page/basic/test.js

 // Copyright (c) 2011 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.
 
 // This test runs through an expected use of a live background page:
 // - A live (web-extent) web page is loaded (a.html), which opens the background
 //   page.
 // - The first page is closed and a second live web page is loaded (b.html),
 //   which attempts to get still-running running background page. This second
 //   page also checks a counter which should have a value consistent with being
 //   called once from each of the first and second pages.
 // - The background page closes itself.
 
 var pageA;
 var pageB;
 var backgroundPageResponded = false;
 
 var pagePrefix =
-    'http://a.com:PORT/files/extensions/api_test/app_background_page/common';
+    'http://a.com:PORT/extensions/api_test/app_background_page/common';
 
 // Dispatch "tunneled" functions from the live web pages to this testing page.
 chrome.extension.onRequest.addListener(function(request) {
   window[request.name](request.args);
 });
 
 // At no point should a window be created that contains the background page
 // (bg.html).
 chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
   if (tab.url.match("bg\.html$")) {
@@ skipping 40 matching lines @@
   } else {
     chrome.test.notifyPass();
   }
 }
 
 // The background counter check found an unexpected value (most likely caused
 // by an unwanted navigation.
 function onCounterError() {
   chrome.test.notifyFail("checkCounter found an unexpected value");
 }