title: Why call provision request while using exoplayer to play widevine?
body: <p>I'm trying to play a video protected by DRM (Widevine) through ExoPlayer Android library. But I observe that some google api was called when playing the content, like: <code>https://www.googleapis.com/certificateprovisioning/v1/devicecertificates/create?key=AIzaSyB-5OLKTx2iU5mko18DfdwK5611JIjbUhE&amp;signedRequest=CloKTAgAEkgAAAACAAARXQ2Uk20H84uZwd-GgomF4yknNzh91QhUZHxuThGrF5WLuZE6xUzyEWRwhnBlUVV0dmDoaIS2bF9yCUtW-awQeLkSBA-nt1QaBAgAEgASII3yfAKXhcwZhE1ft-BI3AQMe_jgIefj-QS8F9kOZtzt</code>.</p>
  
  <p>I don know why google api was called? And how can I avoid to call it ?</p>