Wire up BWE stats through WebrtcSession so that they are filled in both for audio and video calls.

webrtc/pc/rtcstatscollector.cc

Index: webrtc/pc/rtcstatscollector.cc
diff --git a/webrtc/pc/rtcstatscollector.cc b/webrtc/pc/rtcstatscollector.cc
index d9da0729eda2275986ded8535f334a5816c82d4b..ca995327d5f21d19623e36c290c5a2941f1df431 100644
--- a/webrtc/pc/rtcstatscollector.cc
+++ b/webrtc/pc/rtcstatscollector.cc
@@ -652,9 +652,16 @@ void RTCStatsCollector::GetStatsReport(
     // implemented to invoke on the signaling thread.
     track_to_id_ = PrepareTrackToID_s();
 
-    invoker_.AsyncInvoke<void>(RTC_FROM_HERE, network_thread_,
+    // Prepare |call_stats_| here since GetCallStats() will hop to the worker
+    // thread.
+    // TODO(holmer): To avoid the hop we could move BWE and BWE stats to the
+    // network thread, where it more naturally belongs.
+    call_stats_ = pc_->session()->GetCallStats();
+
+    invoker_.AsyncInvoke<void>(
+        RTC_FROM_HERE, network_thread_,
         rtc::Bind(&RTCStatsCollector::ProducePartialResultsOnNetworkThread,
-            rtc::scoped_refptr<RTCStatsCollector>(this), timestamp_us));
+                  rtc::scoped_refptr<RTCStatsCollector>(this), timestamp_us));
     ProducePartialResultsOnSignalingThread(timestamp_us);
   }
 }
@@ -704,9 +711,9 @@ void RTCStatsCollector::ProducePartialResultsOnNetworkThread(
         timestamp_us, transport_cert_stats, report.get());
     ProduceCodecStats_n(
         timestamp_us, *track_media_info_map_, report.get());
-    ProduceIceCandidateAndPairStats_n(
-        timestamp_us, *session_stats, track_media_info_map_->video_media_info(),
-        report.get());
+    ProduceIceCandidateAndPairStats_n(timestamp_us, *session_stats,
+                                      track_media_info_map_->video_media_info(),
+                                      call_stats_, report.get());
     ProduceRTPStreamStats_n(
         timestamp_us, *session_stats, *track_media_info_map_, report.get());
     ProduceTransportStats_n(
@@ -835,9 +842,11 @@ void RTCStatsCollector::ProduceDataChannelStats_s(
 }
 
 void RTCStatsCollector::ProduceIceCandidateAndPairStats_n(
-      int64_t timestamp_us, const SessionStats& session_stats,
-      const cricket::VideoMediaInfo* video_media_info,
-      RTCStatsReport* report) const {
+    int64_t timestamp_us,
+    const SessionStats& session_stats,
+    const cricket::VideoMediaInfo* video_media_info,
+    const Call::Stats& call_stats,
+    RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
   for (const auto& transport_stats : session_stats.transport_stats) {
     for (const auto& channel_stats : transport_stats.second.channel_stats) {
@@ -879,24 +888,18 @@ void RTCStatsCollector::ProduceIceCandidateAndPairStats_n(
               static_cast<double>(*info.current_round_trip_time_ms) /
               rtc::kNumMillisecsPerSec;
         }
-        if (info.best_connection && video_media_info &&
-            !video_media_info->bw_estimations.empty()) {
+        if (info.best_connection) {
           // The bandwidth estimations we have are for the selected candidate
           // pair ("info.best_connection").
-          RTC_DCHECK_EQ(video_media_info->bw_estimations.size(), 1);
-          RTC_DCHECK_GE(
-              video_media_info->bw_estimations[0].available_send_bandwidth, 0);
-          RTC_DCHECK_GE(
-              video_media_info->bw_estimations[0].available_recv_bandwidth, 0);
-          if (video_media_info->bw_estimations[0].available_send_bandwidth) {
+          RTC_DCHECK_GE(call_stats.send_bandwidth_bps, 0);
+          RTC_DCHECK_GE(call_stats.recv_bandwidth_bps, 0);
+          if (call_stats.send_bandwidth_bps > 0) {
             candidate_pair_stats->available_outgoing_bitrate =
-                static_cast<double>(video_media_info->bw_estimations[0]
-                                        .available_send_bandwidth);
+                static_cast<double>(call_stats.send_bandwidth_bps);
           }
-          if (video_media_info->bw_estimations[0].available_recv_bandwidth) {
+          if (call_stats.recv_bandwidth_bps > 0) {
             candidate_pair_stats->available_incoming_bitrate =
-                static_cast<double>(video_media_info->bw_estimations[0]
-                                        .available_recv_bandwidth);
+                static_cast<double>(call_stats.recv_bandwidth_bps);
           }
         }
         candidate_pair_stats->requests_received =