Take notification API out of experimental.

chrome/test/data/extensions/api_test/notification/api/by_user/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.
-
-const notification = chrome.experimental.notification;
-var theOnlyTestDone = null;
-
-var notificationData = {
-  templateType: "basic",
-  iconUrl: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAA" +
-           "CNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHw" +
-           "AAAABJRU5ErkJggg==",
-  title: "Attention!",
-  message: "Check out Cirque du Soleil"
-};
-
-var results = {
-  FOO: false,
-  BAR: true,
-  BAT: false,
-  BIFF: false,
-  BLAT: true,
-  BLOT: true
-};
-
-function createCallback(id) { }
-
-var onClosedHooks = {
-  BIFF: function() {
-    notification.create("BLAT", notificationData, createCallback);
-    notification.create("BLOT", notificationData, createCallback);
-  },
-};
-
-function onClosedListener(id, by_user) {
-  if (results[id] !== by_user) {
-    chrome.test.notifyFail("Notification " + id +
-                           " closed with bad by_user param ( "+ by_user +" )");
-    return;
-  }
-  chrome.test.notifyPass();
-  delete results[id];
-
-  if (typeof onClosedHooks[id] === "function")
-    onClosedHooks[id]();
-
-  if (Object.keys(results).length === 0)
-    theOnlyTestDone();
-}
-
-notification.onClosed.addListener(onClosedListener);
-
-function theOnlyTest() {
-  theOnlyTestDone = chrome.test.callbackAdded();
-
-  notification.create("FOO", notificationData, createCallback);
-  notification.create("BAR", notificationData, createCallback);
-  notification.create("BAT", notificationData, createCallback);
-  notification.create("BIFF", notificationData, createCallback);
-}
-
-chrome.test.runTests([ theOnlyTest ]);