anchor.diff:  
     /// Creates a game room
     GameRoom _createGameRoom(ProtocolPeerRoom room) {
  -    _GameRoom gameRoom = new _GameRoom<_P2PGame, L, R, Player>(this, room, _gameRoomRendererFactory);
  +    _GameRoom gameRoom = new _GameRoom<_P2PGame, L, R, Player>(
  +        this, room, _gameRoomRendererFactory);
       return gameRoom;
     }
   
  
positive.code: 
  /// Interface for the P2PGame class
  abstract class SynchronizedP2PGame<L extends LocalPlayer, R extends RemotePlayer, G extends SynchronizedGameRoom>
      extends P2PGame<L, R, G> {
  }
  
  ///
  abstract class PlayerFactory<L extends LocalPlayer, R extends RemotePlayer> {
  
negative.code:     this.playerFactory = f;
    }
  
    void setGameRoomRendererFactory(
        GameRoomRendererFactory<G> gameRoomRendererFactory) {
      this._gameRoomRendererFactory = gameRoomRendererFactory;
    }
  }
  