Pass time constant to bwe smoothing filter.

webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc

Index: webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc b/webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc
index 3f26e592ae4d84dae03348bdfc1cb9d4aa25ac33..c242bf4f278250fb84441761c45270537363c7ec 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc
+++ b/webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc
@@ -116,6 +116,15 @@ TEST_F(DelayBasedBweTest, ProbeDetectionSlowerArrivalHighBitrate) {
   EXPECT_NEAR(bitrate_observer_.latest_bitrate(), 4000000u, 10000u);
 }
 
+TEST_F(DelayBasedBweTest, GetProbingInterval) {
+  int64_t default_interval_ms = bitrate_estimator_->GetProbingIntervalMs();
+  EXPECT_GT(default_interval_ms, 0);
+  CapacityDropTestHelper(1, true, 567, 0);
+  int64_t interval_ms = bitrate_estimator_->GetProbingIntervalMs();
+  EXPECT_GT(interval_ms, 0);
+  EXPECT_NE(interval_ms, default_interval_ms);
+}
+
 TEST_F(DelayBasedBweTest, InitialBehavior) {
   InitialBehaviorTestHelper(674840);
 }