MediaCodec.stop() call may hang in some rear cases. To avoid application hang this call need to be done on separate thread and possible error reported back to application. Application may elect to continue executing and use another codec instance for encoding/decoding or stop the call and exit. BUG=b/24339249 R=magjed@webrtc.org Review URL: https://codereview.webrtc.org/1425143005 . Cr-Commit-Position: refs/heads/master@{#10467}