if (session) {
  var mediaInfo = new chrome.cast.media.MediaInfo("http://localhost/tom_www/CastTom/music.mp3", "audio/mpeg");
  var request = new chrome.cast.media.LoadRequest(mediaInfo);
  session.loadMedia(
    request,
    onMediaDiscovered.bind(this, 'loadMedia'),
    onMediaError
  );
} else {
  console.log("No session available, connect first");
}