Allowing buffering a LNTF (loss notification) feedback message in RTCPSender

Loss notifications may either be sent immediately, or wait until another
RTCP feedback message is sent.

Bug: webrtc:10336
Change-Id: I40601d9fa1dec6c17b2ce905cb0c8cd2dcff7893
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/139242
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28142}
diff --git a/test/rtcp_packet_parser.h b/test/rtcp_packet_parser.h
index 809509d..4916195 100644
--- a/test/rtcp_packet_parser.h
+++ b/test/rtcp_packet_parser.h
@@ -105,6 +105,7 @@
     return &transport_feedback_;
   }
   uint32_t sender_ssrc() const { return sender_ssrc_; }
+  size_t processed_rtcp_packets() const { return processed_rtcp_packets_; }
 
  private:
   PacketCounter<rtcp::App> app_;
@@ -124,6 +125,7 @@
   PacketCounter<rtcp::Tmmbr> tmmbr_;
   PacketCounter<rtcp::TransportFeedback> transport_feedback_;
   uint32_t sender_ssrc_ = 0;
+  size_t processed_rtcp_packets_ = 0;
 };
 
 }  // namespace test