static getFactory(uri, mimeType) {
    const ManifestParser = shaka.media.ManifestParser;

    // Try using the MIME type we were given.
    if (mimeType) {
      const factory = ManifestParser.parsersByMime.get(mimeType.toLowerCase());
      if (factory) {
        return factory;
      }

      shaka.log.warning(
          'Could not determine manifest type using MIME type ', mimeType);
    }

    throw new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.MANIFEST,
        shaka.util.Error.Code.UNABLE_TO_GUESS_MANIFEST_TYPE,
        uri,
        mimeType);
  }
Get a factory that can create a manifest parser that should be able to
parse the manifest at |uri|.

@param {string} uri
@param {?string} mimeType
@return {shaka.extern.ManifestParser.Factory}