title: How to restart video on Exoplayer after ExoPlayer.STATE_ENDED
body: <p>I'm using <strong>Exoplayer</strong> with a base of the <strong>DemoPlayer</strong>. 
  I want to <strong>restart/replay</strong> the video from beginning on some user action <strong>after</strong> that <strong>ExoPlayer.STATE_ENDED</strong> is dispatched. </p>
  
  <p>I've tried to use <code>seekTo(0)</code> and <code>mPlayer.setPlayWhenReady(true);</code> after but it didn't do anything, at all. </p>