static basicInitDataTransform_(initData, initDataType, drmInfo) {
    if (initDataType !== 'skd') {
      return initData;
    }
    const StringUtils = shaka.util.StringUtils;
    const cert = drmInfo.serverCertificate;
    const initDataAsString = StringUtils.fromBytesAutoDetect(initData);
    const contentId = initDataAsString.split('skd://').pop();
    return shaka.drm.FairPlay.initDataTransform(initData, contentId, cert);
  }
Basic initDataTransform configuration.

@param {!Uint8Array} initData
@param {string} initDataType
@param {?shaka.extern.DrmInfo} drmInfo
@return {!Uint8Array}
@private