chromium/chrome/test/data/webapps_integration/standalone/foo/basic.html

<!DOCTYPE html>
<html>
<head>
  <title>Site A Foo</title>
    <script src="/webapps_integration/test_utils.js"></script>
    <script>
      // If a "manifest=/path/to/manifest.json" query argument is provided to
      // the URL accessing this page, that path is injected as the manifest tag.
      // Otherwise, "basic.json" is used as the manifest tag.
      addManifestLinkTag();
    </script>
</head>
<body onload="startWorker('../service_worker.js', { scope: '/webapps_integration/standalone/' })">
  <h1>Site A Foo</h1>
  Service worker returns a response object if it's offline, so the page
  supports the offline environment.
</body>
</html>