Add new view that renders local video using AVCaptureLayerPreview.

webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m

Index: webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m
diff --git a/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m b/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m
index 8de6b959f026150a13fa87be3d1bd9026890096f..51290a05b585bed47fe4074f17bf80b0cbec5026 100644
--- a/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m
+++ b/webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m
@@ -128,18 +128,21 @@
   if (_localVideoTrack == localVideoTrack) {
     return;
   }
-  [_localVideoTrack removeRenderer:_videoCallView.localVideoView];
   _localVideoTrack = nil;
-  [_videoCallView.localVideoView renderFrame:nil];
   _localVideoTrack = localVideoTrack;
-  [_localVideoTrack addRenderer:_videoCallView.localVideoView];
+  RTCAVFoundationVideoSource *source = nil;
+  if ([localVideoTrack.source
+          isKindOfClass:[RTCAVFoundationVideoSource class]]) {
+    source = (RTCAVFoundationVideoSource*)localVideoTrack.source;
+  }
+  _videoCallView.localVideoView.captureSession = source.captureSession;
 }
 
 - (void)setRemoteVideoTrack:(RTCVideoTrack *)remoteVideoTrack {
   if (_remoteVideoTrack == remoteVideoTrack) {
     return;
   }
-  [_remoteVideoTrack removeRenderer:_videoCallView.localVideoView];
+  [_remoteVideoTrack removeRenderer:_videoCallView.remoteVideoView];
   _remoteVideoTrack = nil;
   [_videoCallView.remoteVideoView renderFrame:nil];
   _remoteVideoTrack = remoteVideoTrack;