modifyTimepoints_(patchNode) {
    const TXml = shaka.util.TXml;
    const SegmentTemplate = shaka.dash.SegmentTemplate;

    const paths = TXml.parseXpath(patchNode.attributes['sel'] || '');
    const contextIds = this.getContextIdsFromPath_(paths);

    for (const contextId of contextIds) {
      /** @type {shaka.dash.DashParser.Context} */
      const context = this.contextCache_.get(contextId);
      SegmentTemplate.modifyTimepoints(context, patchNode);
    }
    return contextIds;
  }
Ingests Patch MPD segments into timeline.

@param {!shaka.extern.xml.Node} patchNode
@return {!Array<string>} context ids with updated timeline
@private