Populate "total_round_trip_time" and "round_trip_time_measurements" for remote inbound RTP streams

Spec: https://w3c.github.io/webrtc-stats/#remoteinboundrtpstats-dict*

Adding them into the stats definition as well.

Bug: webrtc:12507
Change-Id: Id467a33fe7bb256655b68819e3ce87ca9af5b25f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/209000
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33363}
diff --git a/pc/rtc_stats_collector.cc b/pc/rtc_stats_collector.cc
index aa3b17b..6cb1dcc 100644
--- a/pc/rtc_stats_collector.cc
+++ b/pc/rtc_stats_collector.cc
@@ -546,6 +546,11 @@
   remote_inbound->round_trip_time =
       static_cast<double>(report_block_data.last_rtt_ms()) /
       rtc::kNumMillisecsPerSec;
+  remote_inbound->total_round_trip_time =
+      static_cast<double>(report_block_data.sum_rtt_ms()) /
+      rtc::kNumMillisecsPerSec;
+  remote_inbound->round_trip_time_measurements =
+      report_block_data.num_rtts();
 
   std::string local_id = RTCOutboundRTPStreamStatsIDFromSSRC(
       media_type == cricket::MEDIA_TYPE_AUDIO, report_block.source_ssrc);