Split LastFir status out of RTCPReceiver::ReceiveInfo

This a pre-step for improving perfomance of the RTCPReceiver
- rest of the ReceiveInfo is tmmbr related and
can be handled only when tmmbr is explicitly enabled.

BUG=webrtc:5565

Review-Url: https://codereview.webrtc.org/2681003003
Cr-Commit-Position: refs/heads/master@{#16667}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_receiver.h b/webrtc/modules/rtp_rtcp/source/rtcp_receiver.h
index b86b030..26defae 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_receiver.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_receiver.h
@@ -119,6 +119,7 @@
   struct PacketInformation;
   struct ReceiveInformation;
   struct ReportBlockWithRtt;
+  struct LastFirStatus;
   // Mapped by remote ssrc.
   using ReceivedInfoMap = std::map<uint32_t, ReceiveInformation>;
   // RTCP report blocks mapped by remote SSRC.
@@ -245,6 +246,7 @@
   ReportBlockMap received_report_blocks_ GUARDED_BY(rtcp_receiver_lock_);
   ReceivedInfoMap received_infos_ GUARDED_BY(rtcp_receiver_lock_);
   int64_t oldest_received_info_ms_ GUARDED_BY(rtcp_receiver_lock_);
+  std::map<uint32_t, LastFirStatus> last_fir_ GUARDED_BY(rtcp_receiver_lock_);
   std::map<uint32_t, std::string> received_cnames_
       GUARDED_BY(rtcp_receiver_lock_);