Add QP sum stats for received streams.

webrtc/video/receive_statistics_proxy.cc

Index: webrtc/video/receive_statistics_proxy.cc
diff --git a/webrtc/video/receive_statistics_proxy.cc b/webrtc/video/receive_statistics_proxy.cc
index 68050ba6a8a440dcc3eb31a4edf22127d99949c0..dac50c3bf18b6b82154db17c60c580034993678c 100644
--- a/webrtc/video/receive_statistics_proxy.cc
+++ b/webrtc/video/receive_statistics_proxy.cc
@@ -395,11 +395,16 @@ void ReceiveStatisticsProxy::DataCountersUpdated(
   }
 }
 
-void ReceiveStatisticsProxy::OnDecodedFrame() {
+void ReceiveStatisticsProxy::OnDecodedFrame(int qp) {
   uint64_t now = clock_->TimeInMilliseconds();
 
   rtc::CritScope lock(&crit_);
   ++stats_.frames_decoded;
+  if (qp != -1) {
+    if (!stats_.qp_sum)
+      stats_.qp_sum = rtc::Optional<uint64_t>(0);
+    *stats_.qp_sum += qp;
+  }

[hbos, 2017/01/25 11:31:12]

Either all frames or no frames should have qp values. If only some of them have
qp values then qp sum will not align with the framesDecoded values and that is a
bug. Should we DCHECK that?

++stats_.frames_decoded;
if (qp) {
  if (!stats_.qp_sum) {
    RTC_DCHECK_EQ(stats_.frames_decoded, 1);
    stats_.qp_sum = rtc::Optional<uint64_t>(0);
  }
  *stats_.qp_sum += *qp;
} else {
  RTC_DCHECK(!stats_.qp_sum);
}

[sakal, 2017/01/25 12:39:34]

Done.

   decode_fps_estimator_.Update(1, now);
   stats_.decode_frame_rate = decode_fps_estimator_.Rate(now).value_or(0);
 }