proxyEvent_(targetName, event) {
    if (!this.player_) {
      // The receiver is destroyed, so it should ignore further events.
      return;
    }

    // Poll and send an update right before we send the event.  Some events
    // indicate an attribute change, so that change should be visible when the
    // event is handled.
    this.pollAttributes_();

    this.sendMessage_({
      'type': 'event',
      'targetName': targetName,
      'event': event,
    }, this.shakaBus_);
  }
@param {string} targetName
@param {!Event} event
@private