static unpackTimeRanges_(ranges) {
    const obj = {
      '__type__': 'TimeRanges',  // a signal to deserialize
      'length': ranges.length,
      'start': [],
      'end': [],
    };

    const TimeRangesUtils = shaka.media.TimeRangesUtils;
    for (const {start, end} of TimeRangesUtils.getBufferedInfo(ranges)) {
      obj['start'].push(start);
      obj['end'].push(end);
    }

    return obj;
  }
@param {!TimeRanges} ranges
@return {!Object}
@private