samples/poppopwin: upgrade to first-class sample

samples/third_party/pop-pop-win/lib/src/canvas/game_audio.dart

Index: samples/third_party/pop-pop-win/lib/src/canvas/game_audio.dart
diff --git a/samples/third_party/pop-pop-win/lib/src/canvas/game_audio.dart b/samples/third_party/pop-pop-win/lib/src/canvas/game_audio.dart
deleted file mode 100644
index b3457a197a38d41c4c3026504a29f4609ae7d876..0000000000000000000000000000000000000000
--- a/samples/third_party/pop-pop-win/lib/src/canvas/game_audio.dart
+++ /dev/null
@@ -1,24 +0,0 @@
-part of ppw_canvas;
-
-class GameAudio {
-  static const String WIN = 'win', CLICK = 'click', POP = 'Pop', FLAG = 'flag',
-      UNFLAG = 'unflag', BOMB = 'Bomb', THROW_DART = 'throw';
-
-  static final EventHandle<String> _audioEventHandle = new EventHandle<String>();
-
-  static Stream<String> get audioEvent => _audioEventHandle.stream;
-
-  static void win() => _audioEventHandle.add(WIN);
-
-  static void click() => _audioEventHandle.add(CLICK);
-
-  static void pop() => _audioEventHandle.add(POP);
-
-  static void flag() => _audioEventHandle.add(FLAG);
-
-  static void unflag() => _audioEventHandle.add(UNFLAG);
-
-  static void bomb() => _audioEventHandle.add(BOMB);
-
-  static void throwDart() => _audioEventHandle.add(THROW_DART);
-}