static hasMediaKeySystemAccess(videoCodec, audioCodec, keySystem) {
    const DrmUtils = shaka.drm.DrmUtils;
    const key = DrmUtils.generateKeySystemCacheKey_(
        videoCodec, audioCodec, keySystem);
    return DrmUtils.memoizedMediaKeySystemAccessRequests_.has(key);
  }
Check does MediaKeySystemAccess cache contains something for following
attributes.

@param {string} videoCodec
@param {string} audioCodec
@param {string} keySystem
@return {boolean}