Revert of Refactored incoming bitrate estimator.

webrtc/modules/congestion_controller/delay_based_bwe.h

Index: webrtc/modules/congestion_controller/delay_based_bwe.h
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe.h b/webrtc/modules/congestion_controller/delay_based_bwe.h
index c44ea12e1c752479f20fa3798d0f9436823918bd..eccd73ac4d49f7daea6b7fd1ae7366b6e6089d50 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe.h
+++ b/webrtc/modules/congestion_controller/delay_based_bwe.h
@@ -48,8 +48,7 @@
   virtual ~DelayBasedBwe();
 
   Result IncomingPacketFeedbackVector(
-      const std::vector<PacketFeedback>& packet_feedback_vector,
-      rtc::Optional<uint32_t> acked_bitrate_bps);
+      const std::vector<PacketFeedback>& packet_feedback_vector);
   void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms);
   bool LatestEstimate(std::vector<uint32_t>* ssrcs,
                       uint32_t* bitrate_bps) const;
@@ -58,11 +57,30 @@
   int64_t GetExpectedBwePeriodMs() const;
 
  private:
+  // Computes a bayesian estimate of the throughput given acks containing
+  // the arrival time and payload size. Samples which are far from the current
+  // estimate or are based on few packets are given a smaller weight, as they
+  // are considered to be more likely to have been caused by, e.g., delay spikes
+  // unrelated to congestion.
+  class BitrateEstimator {
+   public:
+    BitrateEstimator();
+    void Update(int64_t now_ms, int bytes);
+    rtc::Optional<uint32_t> bitrate_bps() const;
+
+   private:
+    float UpdateWindow(int64_t now_ms, int bytes, int rate_window_ms);
+    int sum_;
+    int64_t current_win_ms_;
+    int64_t prev_time_ms_;
+    float bitrate_estimate_;
+    float bitrate_estimate_var_;
+  };
+
   void IncomingPacketFeedback(const PacketFeedback& packet_feedback);
   Result OnLongFeedbackDelay(int64_t arrival_time_ms);
 
-  Result MaybeUpdateEstimate(bool overusing,
-                             rtc::Optional<uint32_t> acked_bitrate_bps);
+  Result MaybeUpdateEstimate(bool overusing);
   // Updates the current remote rate estimate and returns true if a valid
   // estimate exists.
   bool UpdateEstimate(int64_t now_ms,
@@ -76,6 +94,7 @@
   std::unique_ptr<InterArrival> inter_arrival_;
   std::unique_ptr<TrendlineEstimator> trendline_estimator_;
   OveruseDetector detector_;
+  BitrateEstimator receiver_incoming_bitrate_;
   int64_t last_seen_packet_ms_;
   bool uma_recorded_;
   AimdRateControl rate_control_;