Parse MedianSlopeFilter-parameters to the correct variables.

BUG=webrtc:6995

Review-Url: https://codereview.webrtc.org/2631293003
Cr-Commit-Position: refs/heads/master@{#16113}
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe.cc b/webrtc/modules/congestion_controller/delay_based_bwe.cc
index 6338f96..7a20b3e 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe.cc
+++ b/webrtc/modules/congestion_controller/delay_based_bwe.cc
@@ -230,8 +230,8 @@
                                             &trendline_threshold_gain_);
   }
   if (in_median_slope_experiment_) {
-    ReadMedianSlopeFilterExperimentParameters(&trendline_window_size_,
-                                              &trendline_threshold_gain_);
+    ReadMedianSlopeFilterExperimentParameters(&median_slope_window_size_,
+                                              &median_slope_threshold_gain_);
   }
 
   network_thread_.DetachFromThread();