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chromium/chrome/test/data/extensions/platform_apps/app_window_send_message/main.js 

// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

window.onload = function() {
  var iframe = document.createElement('iframe');
  iframe.src = 'data:text/html,<body>hello world.</body>';
  document.body.appendChild(iframe);
};