chromium/chrome/test/data/extensions/api_test/content_scripts/other_extensions/iframe_content.js

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

window.addEventListener('load', function() {
  var parent_extension_page = unescape(location.hash.replace('#', ''));

  console.log('PAGE: Sending content to parent extension page - ' +
              parent_extension_page);
  window.parent.postMessage(document.getElementById('content').innerText,
                            parent_extension_page);
});