Use bayesian estimate of acked bitrate.

webrtc/modules/bitrate_controller/bitrate_controller_impl.cc

Index: webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
index a1f1fd3a70824acd0588e517109f900e6ba2639f..a33d97e0b670eed9684d416f9beec3c5d2279e20 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
@@ -38,9 +38,6 @@ class BitrateControllerImpl::RtcpBandwidthObserverImpl
   void OnReceivedRtcpReceiverReport(const ReportBlockList& report_blocks,
                                     int64_t rtt,
                                     int64_t now_ms) override {
-    if (report_blocks.empty())
-      return;
-
     int fraction_lost_aggregate = 0;
     int total_number_of_packets = 0;