Re-land alexbost's experimental offscreenTabs API.

chrome/test/data/extensions/api_test/offscreen_tabs/tab_util.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 pass = chrome.test.callbackPass;
+var fail = chrome.test.callbackFail;
+var assertEq = chrome.test.assertEq;
+var assertTrue = chrome.test.assertTrue;
+var assertFalse = chrome.test.assertFalse;
+
+var Q_KEY = 113;
+
+function assertEqTabs(tab1, tab2) {
+  assertEq(tab1.id, tab2.id);
+  assertSimilarTabs(tab1, tab2);
+}
+
+function maybeExpandURL(url) {
+  if (url.match('chrome-extension'))
+    return url;
+  return chrome.extension.getURL(url);
+}
+
+function assertSimilarTabs(tab1, tab2) {
+  assertEq(maybeExpandURL(tab1.url), maybeExpandURL(tab2.url));
+  assertEq(tab1.width, tab2.width);
+  assertEq(tab1.height, tab2.height);
+}
+
+function assertTabDoesNotExist(tabId) {
+  var expectedError = 'No offscreen tab with id: ' + tabId + '.';
+  chrome.experimental.offscreenTabs.get(tabId, fail(expectedError));
+}
+
+function getBaseMouseEvent() {
+  return {
+    button: 0,
+    altKey: false,
+    ctrlKey: false,
+    shiftKey: false
+  };
+};
+
+function getKeyboardEvent(keyCode) {
+  return {
+    type: 'keypress',
+    charCode: keyCode,
+    keyCode: keyCode,
+    altKey: false,
+    ctrlKey: false,
+    shiftKey: false
+  };
+}