Report timing frames info in GetStats.

webrtc/pc/statscollector.cc

Index: webrtc/pc/statscollector.cc
diff --git a/webrtc/pc/statscollector.cc b/webrtc/pc/statscollector.cc
index c9325831598549b50c3d1e63de24cddd54ab8ab3..4b2eef8fbe4e26d0a1fbff72b67d7a3577085a44 100644
--- a/webrtc/pc/statscollector.cc
+++ b/webrtc/pc/statscollector.cc
@@ -249,6 +249,8 @@ void ExtractStats(const cricket::VideoReceiverInfo& info, StatsReport* report) {
   for (const auto& i : ints)
     report->AddInt(i.name, i.value);
   report->AddString(StatsReport::kStatsValueNameMediaType, "video");
+  report->AddString(StatsReport::kStatsValueNameTimingFrameInfo,
+                    info.timing_frame_info.ToString());

[hbos, 2017/06/27 14:08:31]

Do not add this stat if timing_frame_info is undefined.

Does this have to rely on "since last GetStats()"? Applications may call
GetStats() in multiple places (have multiple "stats consumers"). This will make
GetStats() break for >1 stats consumer unless each consumer is aware of when the
last call was and what the result of that call was. Can this be avoided?

[ilnik, 2017/06/27 15:23:56]

Multiple stats consumers do not break anything. The purpose of this stat is to
return some single timing frame info. "Since last GetStats " restriction just
makes reports as fine grained as possible. We could return latest available
info, but it is not so interesting as most delayed frame.

 }
 
 void ExtractStats(const cricket::VideoSenderInfo& info, StatsReport* report) {