getBandwidthEstimate(defaultEstimate) {
    if (this.bytesSampled_ < this.minTotalBytes_) {
      return defaultEstimate;
    }

    // Take the minimum of these two estimates.  This should have the effect
    // of adapting down quickly, but up more slowly.
    return Math.min(this.fast_.getEstimate(), this.slow_.getEstimate());
  }
Gets the current bandwidth estimate.

@param {number} defaultEstimate
@return {number} The bandwidth estimate in bits per second.