Add ToString method to AggregatedStats and log stats at the end of a call.

webrtc/video/send_delay_stats.cc

Index: webrtc/video/send_delay_stats.cc
diff --git a/webrtc/video/send_delay_stats.cc b/webrtc/video/send_delay_stats.cc
index 8ae0615c597a6205f81600d4d2150fe9f73a8ec2..1c3fd2a600d8e0662d47904e73c9ccf21873c3d0 100644
--- a/webrtc/video/send_delay_stats.cc
+++ b/webrtc/video/send_delay_stats.cc
@@ -45,6 +45,7 @@ void SendDelayStats::UpdateHistograms() {
     AggregatedStats stats = it.second->GetStats();
     if (stats.num_samples >= kMinRequiredPeriodicSamples) {
       RTC_HISTOGRAM_COUNTS_10000("WebRTC.Video.SendDelayInMs", stats.average);
+      LOG(LS_INFO) << "WebRTC.Video.SendDelayInMs, " << stats.ToString();
     }
   }
 }