static appendQueryToUri(uri, query) {
    if (!query) {
      return uri;
    }

    if (uri.includes('offline:')) {
      return uri;
    }

    const url = new goog.Uri(uri);
    url.getQueryData().set('CMCD', query);
    return url.toString();
  }
Append query args to a uri.

@param {string} uri
@param {string} query
@return {string}