document-picture-in-picture/focus-opener.https.html

<!DOCTYPE html>
<title>Test that a document picture-in-picture window can use Window's focus()
  API to focus its opener window</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<body>
  <iframe></iframe>
<script>
promise_test(async (t) => {
  // Ensure this window is blurred so that we can detect that the
  // document PiP window has focused us.
  const blurPromise = new Promise(async (resolve) => {
    window.addEventListener('blur', resolve, { once: true });
  });

  await test_driver.bless('request PiP window from top window');
  const pipWindow = await documentPictureInPicture.requestWindow();

  // The PiP might be focused automatically.
  // But to be safe that this window is blured, focus the iframe.
  await test_driver.bless('focus inner iframe to blur window');
  document.getElementsByTagName('iframe')[0].focus();
  await blurPromise;

  // Now focus this window from the document picture-in-picture window's
  // context.
  const focusPromise = new Promise(async (resolve) => {
    window.addEventListener('focus', resolve, { once: true });
    await test_driver.bless('focus opener window', pipWindow);
    const focusScript = pipWindow.document.createElement('script');
    // Resolve URI so that we don't implicitly test the base URI of the PIP
    const scriptURI = new URL('support/focus-opener.js', document.baseURI).href;
    focusScript.setAttribute('src', scriptURI);
    pipWindow.document.body.append(focusScript);
  });
  return focusPromise;
});
</script>
</body>