First pass adding android auto and apple carplay support. Android auto tuned on emulator.

lib/main.dart

@@ -127,6 +127,10 @@ class _MainPageState extends State<MainPage> {
     return 'Stopped';
   }
 
+  static const _playbackChannel = MethodChannel(
+    'kryz_go_flutter/playback/methods',
+  );
+
   @override
   void initState() {
     super.initState();
@@ -134,6 +138,21 @@ class _MainPageState extends State<MainPage> {
     _casting.addListener(_handleCastingStateChanged);
     _liveInfo.addListener(_handleLiveInfoChanged);
     _liveInfo.start();
+    _playbackChannel.setMethodCallHandler(_handlePlaybackMethodCall);
+    // Tell native that Flutter is ready to receive method calls.
+    // On Android this unblocks any pending auto_play from Android Auto.
+    if (defaultTargetPlatform == TargetPlatform.android) {
+      _playbackChannel.invokeMethod<void>('flutterReady');
+    }
+  }
+
+  Future<void> _handlePlaybackMethodCall(MethodCall call) async {
+    switch (call.method) {
+      case 'play':
+        await _play();
+      case 'stop':
+        await _stop();
+    }
   }
 
   void _handleAudioStateChanged() {
@@ -144,6 +163,16 @@ class _MainPageState extends State<MainPage> {
     setState(() {
       // Rebuild when playback state changes from the player.
     });
+
+    _syncAutoPlaybackState();
+  }
+
+  void _syncAutoPlaybackState() {
+    if (defaultTargetPlatform != TargetPlatform.android) return;
+    _playbackChannel.invokeMethod<void>('updatePlaybackState', {
+      'isPlaying': _audio.isPlaying,
+      'isBuffering': _audio.isBuffering,
+    });
   }
 
   void _handleLiveInfoChanged() {