chromium/third_party/blink/web_tests/external/wpt/secure-payment-confirmation/resources/iframe-enroll.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>SPC Enrollment iframe</title>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="../utils.sub.js"></script>
<script>
'use strict';

// Setup the listener first, to avoid race conditions.
window.addEventListener('message', async function handler(evt) {
  window.removeEventListener('message', handler);

  if (evt.data.userActivation) {
    test_driver.set_test_context(window.parent);
    await test_driver.bless('user activation');
  }
  // Assume that our parent has already created a virtual authenticator device.
  await createCredential().then(credential => {
    parent.postMessage({type: 'spc_result', id: credential.id, rawId: credential.rawId, error: null}, '*');
  }).catch(e => {
    parent.postMessage({type: 'spc_result', error: e}, '*');
  });
});

// Now let our parent know that we are ready to enroll.
window.parent.postMessage({ type: 'loaded' }, '*');
</script>