Make the BWE threshold adaptive.

webrtc/modules/remote_bitrate_estimator/overuse_estimator.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 128 matching lines @@
   if (num_of_deltas_ > 10*30) {
     alpha = 0.002;
   }
   // Only update the noise estimate if we're not over-using. |beta| is a
   // function of alpha and the time delta since the previous update.
   const double beta = pow(1 - alpha, ts_delta * 30.0 / 1000.0);
   avg_noise_ = beta * avg_noise_
               + (1 - beta) * residual;
   var_noise_ = beta * var_noise_
               + (1 - beta) * (avg_noise_ - residual) * (avg_noise_ - residual);
-  if (var_noise_ < 1e-7) {
-    var_noise_ = 1e-7;
+  if (var_noise_ < 1) {
+    var_noise_ = 1;
   }
 }
 }  // namespace webrtc