Fix race / crash in OnNetworkRouteChanged().

webrtc/modules/bitrate_controller/bitrate_controller_impl.h

Index: webrtc/modules/bitrate_controller/bitrate_controller_impl.h
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_impl.h b/webrtc/modules/bitrate_controller/bitrate_controller_impl.h
index c8bb10282be5677e0ee9976d1038a0f04c2abe0f..7ee6b19380a2ccfb6ef011d732cfcbba0175978a 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_impl.h
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_impl.h
@@ -61,10 +61,7 @@ class BitrateControllerImpl : public BitrateController {
                             uint8_t* fraction_loss,
                             int64_t* rtt) override;
 
-  // RemoteBitrateObserver overrides.
-  void OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
-                               uint32_t bitrate_bps) override;
-  void OnProbeBitrate(uint32_t bitrate_bps) override;
+  void OnDelayBasedBweResult(const DelayBasedBwe::Result& result) override;
 
   int64_t TimeUntilNextProcess() override;
   void Process() override;