text: var images = document.getElementsByTagName('img');
  for (var i = 0, l = images.length; i < l; i++) {
    images[i].src = 'http://placekitten.com/' + images[i].width + '/' + images[i].height;
  }
  
  var s = document.createElement('script');
  // TODO: add "script.js" to web_accessible_resources in manifest.json
  s.src = chrome.extension.getURL('jGravity-min.js');
  s.onload = function() {
      this.remove();
  };
  (document.head || document.documentElement).appendChild(s);