positionIsBuffered_(position, contentType) {
    const bufferedInfo = this.getBufferedInfo_();
    const bufferedRanges = bufferedInfo[contentType];
    if (bufferedRanges && bufferedRanges.length > 0) {
      const bufferStart = bufferedRanges[0].start;
      const bufferEnd = bufferedRanges[bufferedRanges.length - 1].end;
      if (position >= bufferStart && position < bufferEnd) {
        return true;
      }
    }
    return false;
  }
Determine if a position is buffered for a given content type.

@param {!number} position
@param {!string} contentType
@private