chromium/third_party/blink/web_tests/media/video-move-to-document-pip-srcobject.html

<!DOCTYPE html>
<title>Verify that moving a video element to document pip, still plays it normally</title>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<video></video>
<script>
    async_test(function(t) {
        var video = document.querySelector('video');
        navigator.webkitGetUserMedia(
          {video:true},
          t.step_func(stream => video.srcObject = stream),
          t.unreached_func("Did not get mediastream"));
        video.onloadeddata = this.step_func(function() {
            video.onloadeddata = null;
            assert_true(video.networkState == video.NETWORK_IDLE || video.networkState == video.NETWORK_LOADING);
            assert_greater_than(video.readyState, video.HAVE_METADATA);

            // Simulate user activation to enable document pip.
            let mouseAction =
                [{"source": "mouse",
                  "actions": [
                    { "name": "pointerDown", "x": 0, "y": 0 },
                    { "name": "pointerUp" }]}];

            chrome.gpuBenchmarking.pointerActionSequence(mouseAction, this.step_func(function() {
                documentPictureInPicture.requestWindow().then(this.step_func_done(function(pipWindow) {
                    // Move video to document pip and verify that it plays properly.
                    pipWindow.document.body.append(video);
                    assert_true(video.networkState == video.NETWORK_IDLE || video.networkState == video.NETWORK_LOADING);
                    assert_greater_than(video.readyState, video.HAVE_METADATA);
                }));
            }));
        });
    });
</script>