static constructSegmentUris(baseUris, relativeUri, variables) {
    if (!relativeUri) {
      return [];
    }
    return shaka.hls.Utils.constructUris(baseUris, [relativeUri], variables);
  }
@param {!Array<string>} baseUris
@param {?string} relativeUri
@param {?Map<string, string>=} variables
@return {!Array<string>}