TabController _tabController;

   @override
    void initState() {
      _tabController = TabController(length: 2, vsync: this);
      _tabController.addListener(
        () {
          setState(() {});
        },
      );
      super.initState();
    }



    @override
    Widget build(BuildContext context) {
      return DefaultTabController(
               length: 2,
               ....

return TabBarView(
                controller: _tabController,
                physics: _tabController.index == 0
                    ? NeverScrollableScrollPhysics()
                    : AlwaysScrollableScrollPhysics(),
                children: <Widget>[
                  GoogleMap(
                     ...),

                     AnotherWidgetHere()
                     ]
                     ....