chromium/chrome/test/data/extensions/api_test/content_scripts/about_blank_srcdoc/content_script.js

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

if (location.protocol === 'about:') {
  chrome.runtime.sendMessage('message from ' + location.href);
} else if (frameElement && !frameElement.getAttribute('src')) {
  chrome.runtime.sendMessage('message from about:blank');
}

chrome.runtime.onMessage.addListener(function(message) {
  if (message === 'open about:blank popup')
    window.open('about:blank');
});