Fix perf issue when timinig out receivers infos in RTCP.

webrtc/modules/rtp_rtcp/source/rtcp_receiver.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 226 matching lines @@
   rtcp::ReceiveTimeInfo remote_time_info_;
   // Time when the report was received.
   NtpTime last_received_xr_ntp_;
   // Estimated rtt, zero when there is no valid estimate.
   bool xr_rrtr_status_ GUARDED_BY(rtcp_receiver_lock_);
   int64_t xr_rr_rtt_ms_;
 
   // Received report blocks.
   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, std::string> received_cnames_
       GUARDED_BY(rtcp_receiver_lock_);
 
   // The last time we received an RTCP RR.
-  int64_t last_received_rr_ms_;
+  int64_t last_received_rr_ms_ GUARDED_BY(rtcp_receiver_lock_);
 
   // The time we last received an RTCP RR telling we have successfully
   // delivered RTP packet to the remote side.
   int64_t last_increased_sequence_number_ms_;
 
   RtcpStatisticsCallback* stats_callback_ GUARDED_BY(feedbacks_lock_);
 
   RtcpPacketTypeCounterObserver* const packet_type_counter_observer_;
   RtcpPacketTypeCounter packet_type_counter_;
 
   RTCPUtility::NackStats nack_stats_;
 
   size_t num_skipped_packets_;
   int64_t last_skipped_packets_warning_ms_;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_RECEIVER_H_