Add histogram stats for jitter buffer delay and target delay for received video 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 ff419249d4f2fe2bcb65d63115b391d5d7e2cf14..ef0920831c1b04431e12e565835e627323527792 100644
--- a/webrtc/video/receive_statistics_proxy.cc
+++ b/webrtc/video/receive_statistics_proxy.cc
@@ -77,6 +77,17 @@ void ReceiveStatisticsProxy::UpdateHistograms() {
   if (decode_ms != -1)
     RTC_LOGGED_HISTOGRAM_COUNTS_1000("WebRTC.Video.DecodeTimeInMs", decode_ms);
 
+  int jb_delay_ms = jitter_buffer_delay_counter_.Avg(kMinRequiredDecodeSamples);
+  if (jb_delay_ms != -1) {
+    RTC_LOGGED_HISTOGRAM_COUNTS_10000("WebRTC.Video.JitterBufferDelayInMs",
+                                      jb_delay_ms);
+  }
+  int target_delay_ms = target_delay_counter_.Avg(kMinRequiredDecodeSamples);

[stefan-webrtc, 2016/04/26 08:19:26]

We also have "current delay ms" which refers to the actual delay that we impose
on frames, with the goal of reaching the target delay. It can be different
because we're only allowed to change the current delay with 10% per second.
Maybe we should track that too, or instead?

[åsapersson, 2016/04/26 10:23:58]

Ok, added current delay.

+  if (target_delay_ms != -1) {
+    RTC_LOGGED_HISTOGRAM_COUNTS_10000("WebRTC.Video.TargetDelayInMs",
+                                      target_delay_ms);
+  }
+
   int delay_ms = delay_counter_.Avg(kMinRequiredDecodeSamples);
   if (delay_ms != -1)
     RTC_LOGGED_HISTOGRAM_COUNTS_10000("WebRTC.Video.OnewayDelayInMs", delay_ms);
@@ -170,6 +181,8 @@ void ReceiveStatisticsProxy::OnDecoderTiming(int decode_ms,
   stats_.min_playout_delay_ms = min_playout_delay_ms;
   stats_.render_delay_ms = render_delay_ms;
   decode_time_counter_.Add(decode_ms);
+  jitter_buffer_delay_counter_.Add(jitter_buffer_ms);
+  target_delay_counter_.Add(target_delay_ms);

[åsapersson, 2016/04/20 10:48:47]

Let target delay stats replace metric below and then reland
https://codereview.webrtc.org/1905563002/ ?

[åsapersson, 2016/04/26 10:23:58]

Reland CL above?

[stefan-webrtc, 2016/04/26 10:39:42]

Sgtm if Magnus agrees.

   // Network delay (rtt/2) + target_delay_ms (jitter delay + decode time +
   // render delay).
   delay_counter_.Add(target_delay_ms + rtt_ms / 2);