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

webrtc/video_engine/vie_channel.cc

Index: webrtc/video_engine/vie_channel.cc
diff --git a/webrtc/video_engine/vie_channel.cc b/webrtc/video_engine/vie_channel.cc
index 6befe1f88ee3f8bec68e35f5f230db475f727aef..20615be9e845c168536612e26b03da006fb8fc30 100644
--- a/webrtc/video_engine/vie_channel.cc
+++ b/webrtc/video_engine/vie_channel.cc
@@ -135,6 +135,7 @@ ViEChannel::ViEChannel(uint32_t number_of_cores,
                                &send_bitrate_observer_,
                                &send_frame_count_observer_,
                                &send_side_delay_observer_,
+                               &send_packet_observer_,
                                max_rtp_streams)),
       num_active_rtp_rtcp_modules_(1) {
   vie_receiver_.SetRtpRtcpModule(rtp_rtcp_modules_[0]);
@@ -883,6 +884,10 @@ void ViEChannel::RegisterSendSideDelayObserver(
   send_side_delay_observer_.Set(observer);
 }
 
+void ViEChannel::RegisterSendPacketObserver(SendPacketObserver* observer) {
+  send_packet_observer_.Set(observer);
+}
+
 void ViEChannel::RegisterSendBitrateObserver(
     BitrateStatisticsObserver* observer) {
   send_bitrate_observer_.Set(observer);
@@ -1103,6 +1108,7 @@ std::vector<RtpRtcp*> ViEChannel::CreateRtpRtcpModules(
     BitrateStatisticsObserver* send_bitrate_observer,
     FrameCountObserver* send_frame_count_observer,
     SendSideDelayObserver* send_side_delay_observer,
+    SendPacketObserver* send_packet_observer,
     size_t num_modules) {
   RTC_DCHECK_GT(num_modules, 0u);
   RtpRtcp::Configuration configuration;
@@ -1121,6 +1127,7 @@ std::vector<RtpRtcp*> ViEChannel::CreateRtpRtcpModules(
   configuration.send_bitrate_observer = send_bitrate_observer;
   configuration.send_frame_count_observer = send_frame_count_observer;
   configuration.send_side_delay_observer = send_side_delay_observer;
+  configuration.send_packet_observer = send_packet_observer;
   configuration.bandwidth_callback = bandwidth_callback;
   configuration.transport_feedback_callback = transport_feedback_callback;