Pass time constant to bwe smoothing filter.

webrtc/modules/congestion_controller/delay_based_bwe.cc

Index: webrtc/modules/congestion_controller/delay_based_bwe.cc
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe.cc b/webrtc/modules/congestion_controller/delay_based_bwe.cc
index af27505268b736a9bf81c5ab912acf477ded65c6..9620b8f8e6b57267dbced15fb01cce563420eb80 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe.cc
+++ b/webrtc/modules/congestion_controller/delay_based_bwe.cc
@@ -137,7 +137,8 @@ DelayBasedBwe::DelayBasedBwe(Clock* clock)
       receiver_incoming_bitrate_(),
       last_update_ms_(-1),
       last_seen_packet_ms_(-1),
-      uma_recorded_(false) {
+      uma_recorded_(false),
+      probing_interval_estimator_(&rate_control_) {
   network_thread_.DetachFromThread();
 }
 
@@ -269,4 +270,12 @@ void DelayBasedBwe::SetMinBitrate(int min_bitrate_bps) {
   // be called from the network thread in the future.
   rate_control_.SetMinBitrate(min_bitrate_bps);
 }
+
+int DelayBasedBwe::GetProbingIntervalMs() const {
+  auto probing_interval_ms = probing_interval_estimator_.GetIntervalMs();

[stefan-webrtc, 2016/11/22 16:39:05]

int

[michaelt, 2016/11/23 12:28:29]

Its not a int.
GetIntervalMs() returns a optional. 

I changed auto to Optional<int64_t>.

[stefan-webrtc, 2016/11/24 10:40:45]

Ah. Why do we return an optional from the estimator if we're not making use of
it?

[michaelt, 2016/11/24 13:47:18]

Right this don't make sense here. 
I removed the optional and report a default interval instead.

+  if (!probing_interval_ms)
+    return 0;
+
+  return *probing_interval_ms;
+}
 }  // namespace webrtc