isBufferedImpl_(type, time) {
    if (!this.segments[type]) {
      throw new Error('unexpected type');
    }

    const first = this.segments[type].indexOf(true);
    const last = this.segments[type].lastIndexOf(true);
    if (first < 0 || last < 0) {
      return false;
    }

    return time >= this.toTime_(type, first) &&
        time < this.toTime_(type, last);
  }
@param {string} type
@param {number} time
@return {boolean}
@private