[Extensions] Propagate activeTab hosts to extension background pages

chrome/test/data/extensions/api_test/active_tab/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.
 
 var assertEq = chrome.test.assertEq;
 var assertFalse = chrome.test.assertFalse;
 var assertTrue = chrome.test.assertTrue;
 var callbackFail = chrome.test.callbackFail;
 var callbackPass = chrome.test.callbackPass;
 
 var RoleType = chrome.automation.RoleType;
 
-chrome.browserAction.onClicked.addListener(function() {
-  chrome.tabs.executeScript({ code: 'true' }, callbackPass());
+function canXhr(url) {
+  assertFalse(url == null);
+  var xhr = new XMLHttpRequest();
+  xhr.open('GET', url, false);
+  var success = true;
+  try {
+    xhr.send();
+  } catch(e) {
+    assertEq('NetworkError', e.name);
+    success = false;
+  }
+  return success;
+}
+
+var cachedUrl = null;
+var iframeDone = null;
+
+chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
+  if (request.message == 'xhr') {
+    sendResponse({url: cachedUrl});
+  } else {
+    assertTrue(request.success);
+    iframeDone();
+  }
+});
+
+var iframeUrl = chrome.extension.getURL('iframe.html');
+var injectIframe =
+    'var iframe = document.createElement("iframe");\n' +
+    'iframe.src = "' + iframeUrl + '";\n' +
+    'document.body.appendChild(iframe);\n';
+
+chrome.browserAction.onClicked.addListener(function(tab) {
+  iframeDone = chrome.test.callbackAdded();
+  cachedUrl = tab.url;
+  chrome.tabs.executeScript({ code: injectIframe }, callbackPass());
+  assertTrue(canXhr(tab.url));
+
   chrome.automation.getTree(callbackPass(function(rootNode) {
     assertFalse(rootNode == undefined);
     assertEq(RoleType.rootWebArea, rootNode.role);
-    chrome.test.succeed();
   }));
 });
 
 chrome.webNavigation.onCompleted.addListener(function(details) {
   chrome.tabs.executeScript({ code: 'true' }, callbackFail(
          'Cannot access contents of url "' + details.url +
          '". Extension manifest must request permission to access this host.'));
 
   chrome.automation.getTree(callbackFail(
       'Cannot request automation tree on url "' + details.url +
         '". Extension manifest must request permission to access this host.'));
+
+  assertFalse(canXhr(details.url));
 });