lite_page_test.html | Explore in Territory

<html>
  <head>
    <meta name="viewport" content="width=device-width" />
    <script>
      if (window == window.top) {
        document.title = "Main frame";
      } else {
        document.title = "Subframe";
        window.domAutomationController.send("Subframe");
      }
    </script>
  </head>
  <body>
    <h1>Test page for Lite Page Server Previews.</h1>
  </body>
</html>

chromium/chrome/test/data/previews/lite_page_test.html