getEstimate_(id) {
    let bitRate = this.estimateByStreamId_.get(id);

    if (bitRate == null) {
      bitRate = 0;
      shaka.log.error(
          'Asking for bitrate of stream not given to the estimator');
    }

    if (bitRate == 0) {
      shaka.log.warning(
          'Using bitrate of 0, this stream won\'t affect progress');
    }

    return bitRate;
  }
@param {number} id
@return {number}
@private