RTCMediaStreamTrackStats.framesSent collected by RTCStatsCollector.

webrtc/api/rtcstatscollector.cc

Index: webrtc/api/rtcstatscollector.cc
diff --git a/webrtc/api/rtcstatscollector.cc b/webrtc/api/rtcstatscollector.cc
index 0747c8d2761ac560e0106a41cfeec33d00837069..48452b70f001867cb9aa0bf82b6195236dc230a0 100644
--- a/webrtc/api/rtcstatscollector.cc
+++ b/webrtc/api/rtcstatscollector.cc
@@ -452,6 +452,7 @@ void ProduceMediaStreamAndTrackStats(
                 sender_info->send_frame_height);
             video_track_stats->frames_per_second = static_cast<double>(
                 sender_info->framerate_sent);
+            video_track_stats->frames_sent = sender_info->frames_encoded;

[hbos, 2016/12/29 15:34:59]

This is the same as RTCOutboundRTPStreamStats.framesEncoded added in
https://codereview.webrtc.org/2588373005/diff/20001/webrtc/api/rtcstatscollec...
!

[hta-webrtc, 2017/01/02 16:00:12]

The reason why the stats have two variables is that we might drop some frames
due to congestion control after encoding them.
Add a TODO that says "will reduce this by frames dropped due to congestion
control when available".

[hbos, 2017/01/19 10:41:16]

Done.

           }
         } else {
           const cricket::VideoReceiverInfo* receiver_info =