formatMilliseconds(ms, granularity = undefined) {
    return this._formatNumberWithGranularity(ms, granularity, {
      style: 'unit',
      unit: 'millisecond',
      unitDisplay: 'short',
    });
  }
@param {number} ms
@param {number=} granularity Controls how coarse the displayed value is.
                             If undefined, the number will be displayed in full.
@return {string}