Calculate JitterBufferDelayInMs in the new jitter buffer.

webrtc/modules/video_coding/frame_buffer2.cc

Index: webrtc/modules/video_coding/frame_buffer2.cc
diff --git a/webrtc/modules/video_coding/frame_buffer2.cc b/webrtc/modules/video_coding/frame_buffer2.cc
index bf1760ec279052482152c602ec3b6e0d21db7653..279c613424a7dde7154aa1ea0bad786c809d5e84 100644
--- a/webrtc/modules/video_coding/frame_buffer2.cc
+++ b/webrtc/modules/video_coding/frame_buffer2.cc
@@ -45,9 +45,7 @@ FrameBuffer::FrameBuffer(Clock* clock,
       num_frames_history_(0),
       num_frames_buffered_(0),
       stopped_(false),
-      protection_mode_(kProtectionNack),
-      num_total_frames_(0),
-      num_key_frames_(0) {}
+      protection_mode_(kProtectionNack) {}
 
 FrameBuffer::~FrameBuffer() {
   UpdateHistograms();
@@ -133,6 +131,8 @@ FrameBuffer::ReturnReason FrameBuffer::NextFrame(
     timing_->UpdateCurrentDelay(frame->RenderTime(),
                                 clock_->TimeInMilliseconds());
 
+    UpdateJitterDelay();
+
     PropagateDecodability(next_frame_it->second);
     AdvanceLastDecodedFrame(next_frame_it);
     *frame_out = std::move(frame);
@@ -364,6 +364,16 @@ bool FrameBuffer::UpdateFrameInfoWithIncomingFrame(const FrameObject& frame,
   return true;
 }
 
+void FrameBuffer::UpdateJitterDelay() {
+  int unused;
+  int delay;
+  timing_->GetTimings(&unused, &unused, &unused, &unused, &delay, &unused,
+                      &unused);
+
+  accumulated_delay_ += delay;
+  ++accumulated_delay_samples_;
+}
+
 void FrameBuffer::UpdateHistograms() const {
   rtc::CritScope lock(&crit_);
   if (num_total_frames_ > 0) {
@@ -373,6 +383,11 @@ void FrameBuffer::UpdateHistograms() const {
     RTC_HISTOGRAM_COUNTS_1000("WebRTC.Video.KeyFramesReceivedInPermille",
                               key_frames_permille);
   }
+
+  if (accumulated_delay_samples_ > 0) {
+    RTC_HISTOGRAM_COUNTS_10000("WebRTC.Video.JitterBufferDelayInMs",
+                               accumulated_delay_ / accumulated_delay_samples_);
+  }
 }
 
 }  // namespace video_coding