function makeReference(startTime, endTime, syncTime) {
      const initUris = () => ['test:/init.mp4'];
      const mediaQuality = {
        bandwidth: 200,
        audioSamplingRate: null,
        codecs: 'avc1.4d401f',
        contentType: 'video',
        frameRate: 60,
        height: 540,
        mimeType: 'video/mp4',
        channelsCount: null,
        pixelAspectRatio: null,
        width: 960,
        label: null,
        roles: [],
        language: null,
      };
      const init = new shaka.media.InitSegmentReference(initUris, 0, 615);
      init.mediaQuality = mediaQuality;
      const uris = () => ['test:/main.mp4'];
      return new shaka.media.SegmentReference(
          startTime, endTime, uris, 0, null, init, 0, 0, Infinity,
          [], undefined, undefined, syncTime);
    }
@param {number} startTime
@param {number} endTime
@param {number} syncTime
@return {!shaka.media.SegmentReference}