chromium/chrome/test/data/banners/multiple_manifest_test_page.html

<html>
  <head>
    <title>Web app banner test page</title>
    <script src="main.js"></script>
    <script>
      addManifestLinkTag('manifest_with_id.json');
      addManifestLinkTag('manifest.json');
    </script>
  </head>
  <body>
    The first manifest should be used
  </body>
</html>