Delete unused method OnProbeBitrate.

webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h

Index: webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h
diff --git a/webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h b/webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h
index 596c343699202c2f002d64cc4967c6451e4ec093..aab953c319e9a99e8555ef2ca26bc44019719676 100644
--- a/webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h
+++ b/webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h
@@ -34,7 +34,6 @@ class RemoteBitrateObserver {
   // incoming streams.
   virtual void OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
                                        uint32_t bitrate) = 0;
-  virtual void OnProbeBitrate(uint32_t bitrate) {}
 
   virtual ~RemoteBitrateObserver() {}
 };