static getPlayReadyHeaderObject_(element) {
    const PLAYREADY_RECORD_TYPES = shaka.drm.PlayReady.PLAYREADY_RECORD_TYPES;

    const bytes = shaka.util.Uint8ArrayUtils.fromBase64(
        /** @type {string} */ (shaka.util.TXml.getTextContents(element)));
    const records = shaka.drm.PlayReady.parseMsPro_(bytes);
    const record = records.filter((record) => {
      return record.type === PLAYREADY_RECORD_TYPES.RIGHTS_MANAGEMENT;
    })[0];

    if (!record) {
      return null;
    }

    const xml = shaka.util.StringUtils.fromUTF16(record.value, true);
    const rootElement = shaka.util.TXml.parseXmlString(xml, 'WRMHEADER');
    if (!rootElement) {
      return null;
    }
    return rootElement;
  }
Gets a PlayReady Header Object

@param {!shaka.extern.xml.Node} element
@return {?shaka.extern.xml.Node}
@private