This is passed to handler funtions registered for the AddPlayer built-in message.
| msgData | The extra message data included in the AddPlayerMessage. |
| msgSize | The size of the extra message data included in the AddPlayerMessage. |
| playerControllerId | The playerId of the new player. |
| Deserialize | This method is used to populate a message object from a NetworkReader stream. |
| Serialize | The method is used to populate a NetworkWriter stream from a message object. |