title: Update Chromecast MediaMetadata
body: <p>I'm playing a live HLS stream in a Chromecast app, and I'm wanting to update the MediaMetadata when programmes start/finish.  However I can't find a method to do this.  I can load the stream again with fresh MediaInfo, but I can't just update the existing metadata.  Is there any way to do this?</p>
  
  <p>At present I'm casting from an Android app.</p>
  
  <p>Is there a way to send fresh MediaMetadata to the receiver, or can I pass a custom data message with the information, and update the metadata within the sender using javascript?</p>