Fixed crash when PCF is destroyed before MediaSource/Track in ObjC

Bug: webrtc:9231
Change-Id: I31b86aa560f4ad230c9a94fedebebf320e0370a4
Reviewed-on: https://webrtc-review.googlesource.com/88221
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23981}
diff --git a/sdk/objc/Framework/Classes/PeerConnection/RTCRtpReceiver.mm b/sdk/objc/Framework/Classes/PeerConnection/RTCRtpReceiver.mm
index 1342c16..895c451 100644
--- a/sdk/objc/Framework/Classes/PeerConnection/RTCRtpReceiver.mm
+++ b/sdk/objc/Framework/Classes/PeerConnection/RTCRtpReceiver.mm
@@ -63,7 +63,7 @@
   rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> nativeTrack(
     _nativeRtpReceiver->track());
   if (nativeTrack) {
-    return [RTCMediaStreamTrack mediaTrackForNativeTrack:nativeTrack];
+    return [RTCMediaStreamTrack mediaTrackForNativeTrack:nativeTrack factory:_factory];
   }
   return nil;
 }