Make sure send and receive deltas are positive for remote estimated probe clusters.

webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc

Index: webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc b/webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc
index 4f799b3f7de0b3b4b8cf4003447dc23f562b6dae..2b429a9116fedc3521d4eb9a653b35d37b062b67 100644
--- a/webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc
+++ b/webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.cc
@@ -112,8 +112,11 @@ void RemoteBitrateEstimatorAbsSendTime::ComputeClusters(
         ++current.num_above_min_delta;
       }
       if (!IsWithinClusterBounds(send_delta_ms, current)) {
-        if (current.count >= kMinClusterSize)
+        if (current.count >= kMinClusterSize &&
+            current.send_mean_ms > 0.0f &&
+            current.recv_mean_ms > 0.0f) {
           AddCluster(clusters, &current);
+        }
         current = Cluster();
       }
       current.send_mean_ms += send_delta_ms;
@@ -124,8 +127,11 @@ void RemoteBitrateEstimatorAbsSendTime::ComputeClusters(
     prev_send_time = it->send_time_ms;
     prev_recv_time = it->recv_time_ms;
   }
-  if (current.count >= kMinClusterSize)
+  if (current.count >= kMinClusterSize &&
+      current.send_mean_ms > 0.0f &&
+      current.recv_mean_ms > 0.0f) {
     AddCluster(clusters, &current);
+  }
 }
 
 std::list<Cluster>::const_iterator