Add NetEq::FilteredCurrentDelayMs() and use it in VoiceEngine

webrtc/modules/audio_coding/neteq/include/neteq.h

Index: webrtc/modules/audio_coding/neteq/include/neteq.h
diff --git a/webrtc/modules/audio_coding/neteq/include/neteq.h b/webrtc/modules/audio_coding/neteq/include/neteq.h
index b03cff776504ace37b5c2783c75fef9ff18197aa..1ae7664077509c5e49c73144b43e8789e41f9672 100644
--- a/webrtc/modules/audio_coding/neteq/include/neteq.h
+++ b/webrtc/modules/audio_coding/neteq/include/neteq.h
@@ -223,6 +223,11 @@ class NetEq {
   // Returns the current total delay (packet buffer and sync buffer) in ms.
   virtual int CurrentDelayMs() const = 0;
 
+  // Returns the current total delay (packet buffer and sync buffer) in ms,
+  // with smoothing applied to even out short-time fluctuations due to jitter.
+  // The packet buffer part of the delay is not updated during DTX/CNG periods.
+  virtual int FilteredCurrentDelayMs() const = 0;
+
   // Sets the playout mode to |mode|.
   // Deprecated. Set the mode in the Config struct passed to the constructor.
   // TODO(henrik.lundin) Delete.