Tools/TestWebKitAPI/Tests/WebKitCocoa/ExitFullscreenOnEnterPiP.html

<!DOCTYPE html>
<html>
<head>
    <script>
    window.addEventListener('load', event => {
        let video = document.querySelector('video');
        video.addEventListener('playing', event => {
            try {
                window.webkit.messageHandlers.testHandler.postMessage('playing');
            } catch (e) { }
        });
    }, {once: true});
    </script>
</head>
<button id="enter-video-fullscreen" onclick="document.querySelector('video').webkitEnterFullscreen()">enter video fullscreen</button>
<button id="enter-element-fullscreen" onclick="document.querySelector('#target').webkitRequestFullscreen()">enter element fullscreen</button>
<button id="enter-pip" onclick="document.querySelector('video').webkitSetPresentationMode('picture-in-picture')">enter pip</button>
<button id="exit-pip" onclick="document.querySelector('video').webkitSetPresentationMode('inline')">exit pip</button>
<button id="play" onclick="document.querySelector('video').play()">play video</button>
<body>
    <div id="target">
        <video id="video" playsinline src="test.mp4" />
    </div>
</body>
</html>