function OptionManager(api) {

    /**
     * @private
     * @type {module:echarts/ExtensionAPI}
     */
    this._api = api;

    /**
     * @private
     * @type {Array.<number>}
     */
    this._timelineOptions = [];

    /**
     * @private
     * @type {Array.<Object>}
     */
    this._mediaList = [];

    /**
     * @private
     * @type {Object}
     */
    this._mediaDefault;

    /**
     * -1, means default.
     * empty means no media.
     * @private
     * @type {Array.<number>}
     */
    this._currentMediaIndices = [];

    /**
     * @private
     * @type {Object}
     */
    this._optionBackup;

    /**
     * @private
     * @type {Object}
     */
    this._newBaseOption;
}
@param {module:echarts/model/Global} ecModel
@return {Array.<Object>}