constructor(mapId, opt_profiler) {
    super();

    /** @const @private {!data.RawMapId} The EE map ID for fetching tiles. */
    this.mapId_ = mapId;

    /**
     * Map tile calculation cost will be sent to this profiler, if its enabled
     * flag is set.
     * @private {?data.Profiler}
     * @const
     */
    this.profiler_ = opt_profiler || null;
  }
@param {!data.RawMapId} mapId The EE map ID for fetching this layer's
    tiles.
@param {?data.Profiler=} opt_profiler The profiler to send map tile
    calculation cost to, if any.