PluginManager: Move reference counting in the MediaPlugin

* Ideally we should support this feature by default to allow
future improvements to the plugins management.
* Fixes the major memory corruption that lead to various
crashes on exit in MediaPlayer.

headers/private/media/MediaPlugin.h

@@ -13,6 +13,12 @@ class MediaPlugin {
 public:
 								MediaPlugin();
 	virtual						~MediaPlugin();
+
+private:
+	// needed for plug-in reference count management
+	friend class PluginManager;
+
+			int32				fRefCount;
 };
 
 class Decoder;

headers/private/media/StreamerPlugin.h

@@ -27,10 +27,8 @@ private:
 	virtual void				_ReservedStreamer5();
 
 			MediaPlugin*		fMediaPlugin;
-			int32				fRefCount;
 			uint32				fReserved[5];
 
-	// needed for plug-in reference count management
 	friend class PluginManager;
 };
 

src/kits/media/MediaPlugin.cpp

@@ -8,6 +8,8 @@
 
 
 MediaPlugin::MediaPlugin()
+	:
+	fRefCount(0)
 {
 }
 

src/kits/media/PluginManager.cpp

@@ -635,7 +635,7 @@ PluginManager::CreateStreamer(Streamer** streamer, BUrl url, BDataIO** source)
 		}
 
 		(*streamer)->fMediaPlugin = plugin;
-		(*streamer)->fRefCount += 1;
+		plugin->fRefCount += 1;
 
 		BDataIO* streamSource = NULL;
 		if ((*streamer)->Sniff(url, &streamSource) == B_OK) {
@@ -666,13 +666,14 @@ PluginManager::DestroyStreamer(Streamer* streamer)
 		// since otherwise we may actually unload the code for the
 		// destructor...
 		MediaPlugin* plugin = streamer->fMediaPlugin;
+		delete streamer;
 
-		// Delete the streamer only when every reference is released
-		if (streamer->fRefCount == 1) {
-			delete streamer;
+		// Delete the plugin only when every reference is released
+		if (plugin->fRefCount == 1) {
+			plugin->fRefCount = 0;
 			PutPlugin(plugin);
 		} else
-			streamer->fRefCount -= 1;
+			plugin->fRefCount -= 1;
 	}
 }
 

src/kits/media/StreamerPlugin.cpp

@@ -8,8 +8,7 @@
 
 Streamer::Streamer()
 	:
-	fMediaPlugin(NULL),
-	fRefCount(0)
+	fMediaPlugin(NULL)
 {
 }