<!DOCTYPE html>
<html>
    <head>
        <script>
        function go() {
            var audioContext = new webkitAudioContext();
            audioContext.resume();

            var video = document.getElementsByTagName('video')[0];
            video.play().then(playing).catch(notPlaying);
        }

        function playing() {
            try {
                window.webkit.messageHandlers.testHandler.postMessage('playing');
            } catch(e) {
                window.location = 'callback:playing';
            }
        }

        function notPlaying() {
            try {
                window.webkit.messageHandlers.testHandler.postMessage('not playing');
            } catch(e) { }
        }
        </script>
    </head>
    <body onload="go()">
        <video src="video-with-audio.mp4" muted webkit-playsinline></video>
    </body>
</html>