chromium/third_party/blink/web_tests/external/wpt/permissions-policy/policy-extends-to-sandbox.html

<!DOCTYPE html>
<title>permissions policy treats opaque origins correctly</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
  "use strict";
  async_test(t => {
    let frame = document.createElement('iframe');
    frame.src = "/permissions-policy/resources/sandbox-self.html";
    frame.allow = "fullscreen";
    frame.sandbox = "allow-scripts";

    var handle_message = t.step_func(evt => {
      if (evt.source === frame.contentWindow) {
        assert_equals(evt.data.child, true, "'self' in header should match origin of sandboxed frame.");
        assert_equals(evt.data.grandchild, false, "Opaque origins should not match each other.");
        document.body.removeChild(frame);
        window.removeEventListener('message', handle_message);
        t.done();
      }
    });
    window.addEventListener('message', handle_message);
    document.body.appendChild(frame);
  });
</script>