chromium/third_party/blink/web_tests/external/wpt/reporting/resources/same-origin-report.https.sub.html

<!DOCTYPE HTML>
<html>
<head>
  <title>Generates a CSP violation report and sends it to a same-origin endpoint</title>
</head>
<body>
  <script>
        const img = document.createElement('img');
        img.src = "/reporting/resources/fail.png";
        document.body.appendChild(img);
        // Post back to the main frame that the report should have been queued.
        top.postMessage("done", "*");
  </script>
</body>
</html>