Add videoRenderer.dispose for samples widgets deactivate.

Author: cloudwebrtc

lib/src/basic_sample/get_user_media_sample.dart

@@ -29,6 +29,7 @@ class _GetUserMediaSampleState extends State<GetUserMediaSample> {
     if (_inCalling) {
       _hangUp();
     }
+    _localRenderer.dispose();
   }
 
   initRenderers() async {

lib/src/basic_sample/loopback_sample.dart

@@ -32,6 +32,8 @@ class _MyAppState extends State<LoopBackSample> {
     if (_inCalling) {
       _hangUp();
     }
+    _localRenderer.dispose();
+    _localRenderer.dispose();
   }
 
   initRenderers() async {

lib/src/call_sample/call_sample.dart

@@ -44,6 +44,8 @@ class _CallSampleState extends State<CallSample> {
   deactivate() {
     super.deactivate();
     if (_signaling != null) _signaling.close();
+    _localRenderer.dispose();
+    _localRenderer.dispose();
   }
 
   void _connect() async {