Relanding "Pass time constant to bwe smoothing filter."

webrtc/call/bitrate_allocator.h

Index: webrtc/call/bitrate_allocator.h
diff --git a/webrtc/call/bitrate_allocator.h b/webrtc/call/bitrate_allocator.h
index a5ed26c71b3bebf697d05f41d6e4190d7719bfa8..cd3b2e163bf9523c72f2d64d52aa12550f852ba7 100644
--- a/webrtc/call/bitrate_allocator.h
+++ b/webrtc/call/bitrate_allocator.h
@@ -33,7 +33,9 @@ class BitrateAllocatorObserver {
   // implementation, as bitrate in bps.
   virtual uint32_t OnBitrateUpdated(uint32_t bitrate_bps,
                                     uint8_t fraction_loss,
-                                    int64_t rtt) = 0;
+                                    int64_t rtt,
+                                    int64_t probing_interval_ms) = 0;
+
  protected:
   virtual ~BitrateAllocatorObserver() {}
 };
@@ -61,7 +63,8 @@ class BitrateAllocator {
   // Allocate target_bitrate across the registered BitrateAllocatorObservers.
   void OnNetworkChanged(uint32_t target_bitrate_bps,
                         uint8_t fraction_loss,
-                        int64_t rtt);
+                        int64_t rtt,
+                        int64_t probing_interval_ms);
 
   // Set the start and max send bitrate used by the bandwidth management.
   //
@@ -157,6 +160,7 @@ class BitrateAllocator {
   uint32_t last_non_zero_bitrate_bps_ GUARDED_BY(&sequenced_checker_);
   uint8_t last_fraction_loss_ GUARDED_BY(&sequenced_checker_);
   int64_t last_rtt_ GUARDED_BY(&sequenced_checker_);
+  int64_t last_probing_interval_ms_ GUARDED_BY(&sequenced_checker_);
   // Number of mute events based on too low BWE, not network up/down.
   int num_pause_events_ GUARDED_BY(&sequenced_checker_);
   Clock* const clock_ GUARDED_BY(&sequenced_checker_);