chromium/third_party/blink/web_tests/external/wpt/cookies/samesite/resources/iframe-subresource-report.html

<!DOCTYPE html>
<head>
<script src="/cookies/resources/cookie-helper.sub.js"></script>
<script>
function reportSubresourceCookies() {
  credFetch(SECURE_ORIGIN + "/cookies/resources/list.py")
    .then(r => r.json())
    .then(cookies => { cookies.type = "COOKIES";
                       target = window.opener ? window.opener : window.parent;
                       target.postMessage(cookies, "*");});
}
</script>
</head>
<body onload="reportSubresourceCookies()">