doStatus_(eventType) {
    const callbacks = this.callbackMap_[eventType];
    const self = this;
    if (callbacks) {
      callbacks.forEach(function(callback) {
        try {
          callback();
        } catch (ex) {
          self.handleError_('status-callback exception (ignored) ' + ex);
        }
      });
    }

    const onceCallbacks = this.callbackOnceMap_[eventType];
    if (onceCallbacks) {
      onceCallbacks.forEach(function(callback) {
        callback();
      });
    }

    this.callbackOnceMap_[eventType] = [];
  }
Run status change callbacks.

@param {string} eventType The event type
@private