Tune BWE to be a bit less sensitive to spurious delay events.

webrtc/modules/remote_bitrate_estimator/overuse_detector.cc

 /*
  *  Copyright (c) 2012 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 124 matching lines @@
     last_update_ms_ = now_ms;
 
   if (fabs(modified_offset) > threshold_ + kMaxAdaptOffsetMs) {
     // Avoid adapting the threshold to big latency spikes, caused e.g.,
     // by a sudden capacity drop.
     last_update_ms_ = now_ms;
     return;
   }
 
   const double k = fabs(modified_offset) < threshold_ ? k_down_ : k_up_;
+  const int64_t kMaxTimeDeltaMs = 100;

[stefan-webrtc, 2016/03/10 11:34:41]

This was caught by the existing tests:
TestShortTimeoutAndWrap
TestLongTimeoutAndWrap

They didn't catch it previously because they ran for too long after the timeout
so that the (quicker) filter caught up. Reduced the run time after the timeout
so that we are sure to catch regressions.

[mflodman, 2016/03/10 11:59:33]

Good catch!

[mflodman, 2016/03/10 11:59:33]

After discussions, I agree that 100 is a good threshold to start with and we can
experiment with higher values later. This will rather err on the pre-fairness
behavior and would be a safer step to take.

+  int64_t time_delta_ms = std::min(now_ms - last_update_ms_, kMaxTimeDeltaMs);
   threshold_ +=
-      k * (fabs(modified_offset) - threshold_) * (now_ms - last_update_ms_);
+      k * (fabs(modified_offset) - threshold_) * time_delta_ms;
 
   const double kMinThreshold = 6;
   const double kMaxThreshold = 600;
   threshold_ = std::min(std::max(threshold_, kMinThreshold), kMaxThreshold);
 
   last_update_ms_ = now_ms;
 }
 
 void OveruseDetector::InitializeExperiment() {
   RTC_DCHECK(in_experiment_);
   double k_up = 0.0;
   double k_down = 0.0;
   overusing_time_threshold_ = kOverUsingTimeThreshold;
   if (ReadExperimentConstants(&k_up, &k_down)) {
     k_up_ = k_up;
     k_down_ = k_down;
   }
 }
 }  // namespace webrtc