 + window.location.pathname.replace(/\/[^\/]*$/, '/') + "split-cache-popup.html";
  document.body.appendChild(iframe);

  window.addEventListener("message", function listener(event) {
    if (event.origin !== host.HTTP_ORIGIN) {
      // Ignore messages not from the iframe or opener
      return;
    } else if (typeof(event.data) === "object") {
      // This message came from the opener, pass it on to the iframe
      iframe.contentWindow.postMessage(event.data, host.HTTP_ORIGIN);
    } else if (typeof(eve