Add histogram stats for send delay for a sent video stream.

webrtc/video/send_statistics_proxy.h

Index: webrtc/video/send_statistics_proxy.h
diff --git a/webrtc/video/send_statistics_proxy.h b/webrtc/video/send_statistics_proxy.h
index 7209094fe68a70342de60992ea2acc6e4528ef47..255b55576ab50fea57496492f4298148322a1692 100644
--- a/webrtc/video/send_statistics_proxy.h
+++ b/webrtc/video/send_statistics_proxy.h
@@ -34,7 +34,8 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
                             public BitrateStatisticsObserver,
                             public FrameCountObserver,
                             public VideoEncoderRateObserver,
-                            public SendSideDelayObserver {
+                            public SendSideDelayObserver,
+                            public SendPacketObserver {
  public:
   static const int kStatsTimeoutMs;
 
@@ -58,6 +59,8 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
   void OnSuspendChange(bool is_suspended);
   void OnInactiveSsrc(uint32_t ssrc);
 
+  bool OnSentPacket(int packet_id);
+
  protected:
   // From CpuOveruseMetricsObserver.
   void CpuOveruseMetricsUpdated(const CpuOveruseMetrics& metrics) override;
@@ -86,7 +89,25 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
                             int max_delay_ms,
                             uint32_t ssrc) override;
 
+  void OnSendPacket(uint16_t packet_id,
+                    int64_t capture_time_ms,
+                    uint32_t ssrc) override;
+
  private:
+  // Map holding sent packets (mapped by packet id).
+  class PacketIdLessThan {
+   public:
+    bool operator()(uint16_t seq1, uint16_t seq2) const {
+      return IsNewerSequenceNumber(seq2, seq1);
+    }
+  };
+  struct Packet {
+    Packet() : cap_time_ms(-1), send_time_ms(-1) {}
+    int64_t cap_time_ms;
+    int64_t send_time_ms;
+  };
+  typedef std::map<uint16_t, Packet, PacketIdLessThan> PacketMap;
+
   class SampleCounter {
    public:
     SampleCounter() : sum(0), num_samples(0) {}
@@ -120,6 +141,8 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
   VideoSendStream::StreamStats* GetStatsEntry(uint32_t ssrc)
       EXCLUSIVE_LOCKS_REQUIRED(crit_);
   void UpdateHistograms() EXCLUSIVE_LOCKS_REQUIRED(crit_);
+  void RemoveOld(int64_t now, PacketMap* packets)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_);
 
   Clock* const clock_;
   const VideoSendStream::Config config_;
@@ -144,6 +167,9 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
   SampleCounter bw_resolutions_disabled_counter_ GUARDED_BY(crit_);
   SampleCounter delay_counter_ GUARDED_BY(crit_);
   SampleCounter max_delay_counter_ GUARDED_BY(crit_);
+
+  SampleCounter send_delay_counter_ GUARDED_BY(crit_);
+  PacketMap packets_ GUARDED_BY(crit_);
 };
 
 }  // namespace webrtc