optimize channel test

lib/battery.dart

@@ -52,6 +52,11 @@ class _PlatformChannelState extends State<PlatformChannel> {
   @override
   Widget build(BuildContext context) {
     return Material(
+      child: Scaffold(
+        appBar: AppBar(
+          title: Text('Channel test'),
+        ),
+        body: Center(
           child: Column(
             mainAxisAlignment: MainAxisAlignment.spaceEvenly,
             children: <Widget>[
@@ -71,6 +76,8 @@ class _PlatformChannelState extends State<PlatformChannel> {
               Text(_chargingStatus),
             ],
           ),
+        ),
+      ),
     );
   }
 }

lib/main.dart

@@ -107,6 +107,7 @@ class _MyHomePageState extends State<MyHomePage> {
             ),
             FlatButton(
               child: Text('channel test'),
+              color: Colors.green,
               onPressed: (){Navigator.pushNamed(context, "/channeltest");},
             )
           ],