chromium/third_party/blink/web_tests/external/wpt/mediacapture-streams/support/iframe-MediaStreamTrack-transfer-video.html

<!DOCTYPE html>
<html>
  <head>
    <title>iframe</title>
    <script>
      function onMsg(e) {
          if(e.data instanceof MediaStreamTrack) {
              const track = e.data;
              video = document.getElementById("myvideo");
              video.srcObject = new MediaStream ([track]);
              video.play();

              parent.postMessage({result: 'Success'});
          } else {
              parent.postMessage({
                  result: 'Failure',
                  error: `${e.data} is not a MediaStreamTrack`
              });
        }
      }
      window.addEventListener("message", onMsg);
    </script>
  </head>
  <body>
    <video id="myvideo"></video>
  </body>
</html>