aChunks</code></a> and
 support discarding of buffered chunks.

 <p>To avoid excessive re-buffering, implementations should normally return the size of the
 queue. An example of a case where a smaller value may be returned is if network conditions have
 improved dramatically, allowing chunks to be discarded and re-buffered in a track of
 significantly higher quality. Discarding chunks may allow faster switching to a higher quality
 track in this case.

 <p>Note that even if the source supports discarding of