Only use payload size within the receive/send interval for bitrate probing.

webrtc/modules/congestion_controller/probe_bitrate_estimator.cc

Index: webrtc/modules/congestion_controller/probe_bitrate_estimator.cc
diff --git a/webrtc/modules/congestion_controller/probe_bitrate_estimator.cc b/webrtc/modules/congestion_controller/probe_bitrate_estimator.cc
index 561fde939180b74e0cad8b606952487c984eabbd..d2b81e11903a1010d7c98302d1e37b80419d6572 100644
--- a/webrtc/modules/congestion_controller/probe_bitrate_estimator.cc
+++ b/webrtc/modules/congestion_controller/probe_bitrate_estimator.cc
@@ -48,6 +48,7 @@ ProbingResult ProbeBitrateEstimator::PacketFeedback(
   }
 
   AggregatedCluster* cluster = &clusters_[packet_info.probe_cluster_id];
+
   cluster->first_send_ms =
       std::min(cluster->first_send_ms, packet_info.send_time_ms);
   cluster->last_send_ms =
@@ -57,13 +58,13 @@ ProbingResult ProbeBitrateEstimator::PacketFeedback(
   cluster->last_receive_ms =
       std::max(cluster->last_receive_ms, packet_info.arrival_time_ms);
   cluster->size += packet_info.payload_size * 8;
-  cluster->num_probes += 1;
+  cluster->send_times_ms.insert(packet_info.send_time_ms);

[danilchap, 2016/08/19 14:08:30]

why is it needed?

 
   // Clean up old clusters.
   while (clusters_.size() > kMaxNumSavedClusters)
     clusters_.erase(clusters_.begin());
 
-  if (cluster->num_probes < kMinNumProbesValidCluster)
+  if (cluster->send_times_ms.size() < kMinNumProbesValidCluster)

[danilchap, 2016/08/19 14:08:30]

If you worry two small padding packet is not enough to do the probing
calculation, may be better expand this if instead:
if (cluster->num_probes < kMinProbes || cluster->size < kMinSize)

     return ProbingResult();
 
   float send_interval_ms = cluster->last_send_ms - cluster->first_send_ms;
@@ -74,7 +75,8 @@ ProbingResult ProbeBitrateEstimator::PacketFeedback(
   // the last/first packet we expand the interval by the average inverval
   // between the probing packets.
   float interval_correction =
-      static_cast<float>(cluster->num_probes) / (cluster->num_probes - 1);
+      static_cast<float>(cluster->send_times_ms.size()) /
+      (cluster->send_times_ms.size() - 1);
   send_interval_ms *= interval_correction;
   receive_interval_ms *= interval_correction;