<html>
  <head>
    <title>Loading...</title>
    <script>
      window.onbeforeunload = function(e) {
        // Delay must be slightly bigger than
        // RenderViewHostImpl::kUnloadTimeoutMS to trigger
        // "renderer unresponsive".
        var delay = 1500;
        var finishTime = new Date().getTime() + delay;
        while (new Date() < finishTime) {}
        return null;
      };
    </script>
  </head>
  <body>
    <p>Navigate to another page to trigger beforeunload handler.</p>
  </body>
</html>