fix(ssrc-rewriting) Set track owners to null when remote participant leaves.

JitsiConference.js

         return;
     }
 
-    if (!FeatureFlags.isSsrcRewritingSupported()) {
-        const mediaSessions = this.getMediaSessions();
-        let tracksToBeRemoved = [];
+    const mediaSessions = this.getMediaSessions();
+    let tracksToBeRemoved = [];
 
-        for (const session of mediaSessions) {
-            const remoteTracks = session.peerconnection.getRemoteTracks(id);
+    for (const session of mediaSessions) {
+        const remoteTracks = session.peerconnection.getRemoteTracks(id);
 
-            remoteTracks && (tracksToBeRemoved = [ ...tracksToBeRemoved, ...remoteTracks ]);
-
-            // Update the SSRC owners list.
-            session._signalingLayer.updateSsrcOwnersOnLeave(id);
+        remoteTracks && (tracksToBeRemoved = [ ...tracksToBeRemoved, ...remoteTracks ]);
 
+        // Update the SSRC owners list.
+        session._signalingLayer.updateSsrcOwnersOnLeave(id);
+        if (!FeatureFlags.isSsrcRewritingSupported()) {
             // Remove the ssrcs from the remote description and renegotiate.
             session.removeRemoteStreamsOnLeave(id);
         }
+    }
 
-        // Fire the event before renegotiation is done so that the thumbnails can be removed immediately.
-        tracksToBeRemoved.forEach(track => {
+    tracksToBeRemoved.forEach(track => {
+        if (FeatureFlags.isSsrcRewritingSupported()) {
+            track.setSourceName(null);
+            track.setOwner(null);
+        } else {
+            // Fire the event before renegotiation is done so that the thumbnails can be removed immediately.
             this.eventEmitter.emit(JitsiConferenceEvents.TRACK_REMOVED, track);
-        });
-    }
+        }
+    });
 
     const participant = this.participants.get(id);
 

modules/statistics/RTPStatsCollector.js

 import { MediaType } from '../../service/RTC/MediaType';
 import * as StatisticsEvents from '../../service/statistics/Events';
 import browser from '../browser';
+import FeatureFlags from '../flags/FeatureFlags';
 
 const GlobalOnErrorHandler = require('../util/GlobalOnErrorHandler');
 
                 };
 
                 codecs[participantId] = userCodecs;
-            } else {
+
+            // All tracks in ssrc-rewriting mode need not have a participant associated with it.
+            } else if (!FeatureFlags.isSsrcRewritingSupported()) {
                 logger.error(`No participant ID returned by ${track}`);
             }
         }