Relanding "Pass time constant to bwe smoothing filter."

webrtc/audio/audio_send_stream.h

Index: webrtc/audio/audio_send_stream.h
diff --git a/webrtc/audio/audio_send_stream.h b/webrtc/audio/audio_send_stream.h
index 138f4fca7b7a9a161f438fd93c2174ff4ecd245c..ad8266a4dc481cec0dd6be3d0362777b86764a7c 100644
--- a/webrtc/audio/audio_send_stream.h
+++ b/webrtc/audio/audio_send_stream.h
@@ -56,7 +56,8 @@ class AudioSendStream final : public webrtc::AudioSendStream,
   // Implements BitrateAllocatorObserver.
   uint32_t OnBitrateUpdated(uint32_t bitrate_bps,
                             uint8_t fraction_loss,
-                            int64_t rtt) override;
+                            int64_t rtt,
+                            int64_t probing_interval_ms) override;
 
   const webrtc::AudioSendStream::Config& config() const;
   void SetTransportOverhead(int transport_overhead_per_packet);