Make updatePlayingState private for FVPVideoPlayer

packages/video_player/video_player_avfoundation/darwin/video_player_avfoundation/Sources/video_player_avfoundation/FVPVideoPlayer.m

@@ -37,6 +37,9 @@ @interface FVPVideoPlayer ()
 /// state (e.g., after a seek while paused). If YES, the display link should continue to run until
 /// the next frame is successfully provided.
 @property(nonatomic, assign) BOOL waitingForFrame;
+
+/// Updates the playing state of the video player.
+- (void)updatePlayingState;
 @end
 
 @implementation FVPVideoPlayer

packages/video_player/video_player_avfoundation/darwin/video_player_avfoundation/Sources/video_player_avfoundation/include/video_player_avfoundation/FVPVideoPlayer.h

@@ -52,9 +52,6 @@ NS_ASSUME_NONNULL_BEGIN
                     avFactory:(id<FVPAVFactory>)avFactory
                     registrar:(NSObject<FlutterPluginRegistrar> *)registrar;
 
-/// Updates the playing state of the video player.
-- (void)updatePlayingState;
-
 /// Disposes the video player and releases any resources it holds.
 - (void)dispose;