chromium/chrome/test/data/extensions/user_script_run_at_idle.user.js

// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// ==UserScript==
// @name           Document Idle Test
// @namespace      test
// @description    This script tests document-idle
// @include        *
// @run-at         document-idle
// ==/UserScript==

alert(document.readyState);