Configure VoE NACK through AudioReceiveStream::Config.

webrtc/audio_receive_stream.h

Index: webrtc/audio_receive_stream.h
diff --git a/webrtc/audio_receive_stream.h b/webrtc/audio_receive_stream.h
index 9af84a71fa042039bfd232a5cad26765631e0ca0..16ed7692636a6bea53d004e7030532379864d123 100644
--- a/webrtc/audio_receive_stream.h
+++ b/webrtc/audio_receive_stream.h
@@ -79,6 +79,9 @@ class AudioReceiveStream {
       // for details.
       bool transport_cc = false;
 
+      // See NackConfig for description.
+      NackConfig nack;
+
       // RTP header extensions used for the received stream.
       std::vector<RtpExtension> extensions;
     } rtp;