processSessionData_(tags) {
    for (const tag of tags) {
      const id = tag.getAttributeValue('DATA-ID');
      const uri = tag.getAttributeValue('URI');
      const language = tag.getAttributeValue('LANGUAGE');
      const value = tag.getAttributeValue('VALUE');
      const data = (new Map()).set('id', id);
      if (uri) {
        data.set('uri', shaka.hls.Utils.constructSegmentUris(
            [this.masterPlaylistUri_], uri, this.globalVariables_)[0]);
      }
      if (language) {
        data.set('language', language);
      }
      if (value) {
        data.set('value', value);
      }
      const event = new shaka.util.FakeEvent('sessiondata', data);
      if (this.playerInterface_) {
        this.playerInterface_.onEvent(event);
      }
    }
  }
Process EXT-X-SESSION-DATA tags.

@param {!Array<!shaka.hls.Tag>} tags
@private