Remove GetFeedbackInterval in sender side BWE.

webrtc/modules/congestion_controller/probe_bitrate_estimator.h

Index: webrtc/modules/congestion_controller/probe_bitrate_estimator.h
diff --git a/webrtc/modules/congestion_controller/probe_bitrate_estimator.h b/webrtc/modules/congestion_controller/probe_bitrate_estimator.h
index c25c727dd9b995d4030da9158e82d16ad841e7ef..54e6492340a392f046de1d7c3f65d79734c38d2c 100644
--- a/webrtc/modules/congestion_controller/probe_bitrate_estimator.h
+++ b/webrtc/modules/congestion_controller/probe_bitrate_estimator.h
@@ -26,6 +26,8 @@ class ProbeBitrateEstimator {
   // Returns the estimated bitrate if the probe completes a valid cluster.
   int HandleProbeAndEstimateBitrate(const PacketInfo& packet_info);
 
+  rtc::Optional<int> FetchLastEstimatedBitrateBps();
+
  private:
   struct AggregatedCluster {
     int num_probes = 0;
@@ -42,6 +44,7 @@ class ProbeBitrateEstimator {
   void EraseOldClusters(int64_t timestamp_ms);
 
   std::map<int, AggregatedCluster> clusters_;
+  rtc::Optional<int> estimated_bitrate_bps_;
 };
 
 }  // namespace webrtc