feat(virtual-background): Desktop share as virtual background wip

react/features/stream-effects/virtual-background/JitsiStreamBackgroundEffect.js

@@ -282,5 +282,6 @@ export default class JitsiStreamBackgroundEffect {
         });
 
         this._maskFrameTimerWorker.terminate();
+        this._screenSharing && this._screenSharing.dispose();
     }
 }