[Extensions] Propagate activeTab hosts to extension background pages

chrome/test/data/extensions/api_test/active_tab/iframe.js

+// Copyright 2015 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 canXhr(url) {
+  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;
+}
+
+document.addEventListener('DOMContentLoaded', function() {
+  chrome.runtime.sendMessage({message:'xhr'}, function(response) {
+    var success = canXhr(response.url);
+    chrome.runtime.sendMessage({success:success});
+  });
+});