RTCInboundRTPStreamStats's [fir/pli/nack]_count are collected for video.

webrtc/api/rtcstatscollector.cc

Index: webrtc/api/rtcstatscollector.cc
diff --git a/webrtc/api/rtcstatscollector.cc b/webrtc/api/rtcstatscollector.cc
index fbc6dbc5d3be86ce60aec2fa44beb579f318159c..2fd8138122aa658d97b662411a609628df50d781 100644
--- a/webrtc/api/rtcstatscollector.cc
+++ b/webrtc/api/rtcstatscollector.cc
@@ -126,21 +126,29 @@ void SetInboundRTPStreamStatsFromMediaReceiverInfo(
 
 void SetInboundRTPStreamStatsFromVoiceReceiverInfo(
     const cricket::VoiceReceiverInfo& voice_receiver_info,
-    RTCInboundRTPStreamStats* inbound_stats) {
+    RTCInboundRTPStreamStats* inbound_audio) {
   SetInboundRTPStreamStatsFromMediaReceiverInfo(
-      voice_receiver_info, inbound_stats);
-  inbound_stats->media_type = "audio";
-  inbound_stats->jitter =
+      voice_receiver_info, inbound_audio);
+  inbound_audio->media_type = "audio";
+  inbound_audio->jitter =
       static_cast<double>(voice_receiver_info.jitter_ms) /
           rtc::kNumMillisecsPerSec;
+  // |fir_count|, |pli_count| and |sli_count| are only valid for video and are
+  // purposefully left undefined for audio.
 }
 
 void SetInboundRTPStreamStatsFromVideoReceiverInfo(
     const cricket::VideoReceiverInfo& video_receiver_info,
-    RTCInboundRTPStreamStats* inbound_stats) {
+    RTCInboundRTPStreamStats* inbound_video) {
   SetInboundRTPStreamStatsFromMediaReceiverInfo(
-      video_receiver_info, inbound_stats);
-  inbound_stats->media_type = "video";
+      video_receiver_info, inbound_video);
+  inbound_video->media_type = "video";
+  inbound_video->fir_count =
+      static_cast<uint32_t>(video_receiver_info.firs_sent);
+  inbound_video->pli_count =
+      static_cast<uint32_t>(video_receiver_info.plis_sent);
+  inbound_video->nack_count =
+      static_cast<uint32_t>(video_receiver_info.nacks_sent);

[hta-webrtc, 2016/11/22 09:51:29]

Are we sure these are actually counted (ie never -1)?
If they're -1, we should skip generating the stat, but if they're never -1, we
don't need to bother.

[hbos, 2016/11/22 11:02:45]

Looks like it, they start at 0 and there is code for increasing them.

 }
 
 void SetOutboundRTPStreamStatsFromMediaSenderInfo(