flutter searchbar.md

new AppBar(
          elevation: _appBarElevation,
          backgroundColor: theme.appBarBackgroundColor,
          iconTheme: Theme.of(context).iconTheme,
          brightness: Brightness.light,
          flexibleSpace: new Container(
              decoration: new BoxDecoration(
                  border: new Border(
                      bottom: new BorderSide(color: theme.dividerColor)))),
          title: Row(
            children: <Widget>[
              Expanded(
                child: Padding(
                  padding: const EdgeInsets.symmetric(vertical: 12.0),
                  child: Container(padding: const EdgeInsets.fromLTRB(15.0,0.0, 0.0, 0.0),
                    decoration: new BoxDecoration(
                       borderRadius: BorderRadius.circular(4.0),color:
                    Color(0xFFEFEFF0),shape: BoxShape.rectangle),child: TextField(style: TextStyle(color: Colors.black,fontSize: 12.0),decoration: InputDecoration(border: InputBorder.none),),
                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 12.0),
                child: new MaterialButton(
                  minWidth: 40.0,
                  textColor: Colors.black,
                  child: new Text("Clear"),
                  onPressed: () => {},
                  splashColor: theme.appBarBackgroundColor,
                ),
              )
            ],
          ),
          centerTitle: true,
        )