Make the BWE threshold adaptive.

webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc

Index: webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc b/webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc
index ab8f4db8262d62aa1c27e759e512bb62b846a281..36571cccaf3639cf0546a686e0fc1a93659515d8 100644
--- a/webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc
+++ b/webrtc/modules/remote_bitrate_estimator/mimd_rate_control.cc
@@ -93,8 +93,7 @@ void MimdRateControl::SetRtt(int64_t rtt) {
   rtt_ = rtt;
 }
 
-RateControlRegion MimdRateControl::Update(const RateControlInput* input,
-                                          int64_t now_ms) {
+void MimdRateControl::Update(const RateControlInput* input, int64_t now_ms) {
   assert(input);
 
   // Set the initial bit rate value to what we're receiving the first half
@@ -116,11 +115,10 @@ RateControlRegion MimdRateControl::Update(const RateControlInput* input,
     // on an over-use.
     current_input_._noiseVar = input->_noiseVar;
     current_input_._incomingBitRate = input->_incomingBitRate;
-    return rate_control_region_;
+    return;
   }
   updated_ = true;
   current_input_ = *input;
-  return rate_control_region_;
 }
 
 void MimdRateControl::SetEstimate(int bitrate_bps, int64_t now_ms) {