Update the BWE when the network route changes.

webrtc/modules/congestion_controller/include/congestion_controller.h

Index: webrtc/modules/congestion_controller/include/congestion_controller.h
diff --git a/webrtc/modules/congestion_controller/include/congestion_controller.h b/webrtc/modules/congestion_controller/include/congestion_controller.h
index da8719d33a73a86c370a34fb2ac4f34658ecf58e..55442f61c419fbbf53274bec8d4f71d7e5eb7e88 100644
--- a/webrtc/modules/congestion_controller/include/congestion_controller.h
+++ b/webrtc/modules/congestion_controller/include/congestion_controller.h
@@ -70,6 +70,11 @@ class CongestionController : public CallStatsObserver, public Module {
   virtual void SetBweBitrates(int min_bitrate_bps,
                               int start_bitrate_bps,
                               int max_bitrate_bps);
+  // Resets both the BWE state and the bitrate estimator. Note the first
+  // argument is the bitrate_bps.
+  virtual void ResetBweAndBitrates(int bitrate_bps,
+                                   int min_bitrate_bps,
+                                   int max_bitrate_bps);
   virtual void SignalNetworkState(NetworkState state);
   virtual BitrateController* GetBitrateController() const;
   virtual RemoteBitrateEstimator* GetRemoteBitrateEstimator(
@@ -100,6 +105,7 @@ class CongestionController : public CallStatsObserver, public Module {
   bool HasNetworkParametersToReportChanged(uint32_t bitrate_bps,
                                            uint8_t fraction_loss,
                                            int64_t rtt);
+
   Clock* const clock_;
   Observer* const observer_;
   const std::unique_ptr<PacketRouter> packet_router_;