<html>
  <head>
    <script>
      // Note, this page does not enter bfcache because of an HTTP header.

      // Ensure layout is flushed before doing anything with scrolling.
      function flushAndExecute(callback) {
        window.requestAnimationFrame(function() {
          setTimeout(callback);
        });
      }

      var bc = new BroadcastChannel("notbfcached");
      bc.onmessage = (msgEvent) => {
        if (msgEvent.data == "scroll") {
          flushAndExecute(() => {  window.scrollTo(0, 4000); });
        } else if (msgEvent.data == "getScrollY") {
          flushAndExecute(() => { bc.postMessage({ scrollY: window.scrollY}); });
        } else if (msgEvent.data == "back") {
          flushAndExecute(() => { bc.close(); history.back(); });
        } else if (msgEvent.data == "close") {
          bc.postMessage("closed");
          bc.close();
          window.close();
        }
      };
      window.onpageshow = (event) => {
        bc.postMessage({command: "pageshow", persisted: event.persisted});
      };
    </script>
  </head>
  <body>
    <div style="height: 5000px; border: 1px solid black;">content</div>
  </body>
</html>
