abortPrefetchedSegment_(reference) {
    const logPrefix = shaka.media.SegmentPrefetch.logPrefix_(this.stream_);

    let prefetchMap = this.segmentPrefetchMap_;
    if (reference instanceof shaka.media.InitSegmentReference) {
      prefetchMap = this.initSegmentPrefetchMap_;
    }

    const segmentPrefetchOperation = prefetchMap.get(reference);
    prefetchMap.delete(reference);

    if (segmentPrefetchOperation) {
      segmentPrefetchOperation.abort();
      if (reference instanceof shaka.media.SegmentReference) {
        shaka.log.debug(
            logPrefix,
            'pop and abort prefetched segment at time:', reference.startTime);
      } else {
        shaka.log.debug(logPrefix, 'pop and abort prefetched init segment');
      }
    }
  }
Remove a segment from prefetch map and abort it.
@param {!(shaka.media.SegmentReference|
          shaka.media.InitSegmentReference)} reference
@private