<!DOCTYPE html>
<html>
<head>
    <script>
    window.addEventListener('load', async event => {
        var context = new webkitAudioContext();
        context.addEventListener('statechange', statechange);
        node = context.createBufferSource();
        node.connect(context.destination);
        context.resume();
    });
    
    function statechange(event) {
        var context = event.target;
        var message = context.state === 'running' ? 'playing' : 'not playing';
        window.webkit.messageHandlers.testHandler.postMessage(message);
    }
    </script>
</head>
</html>