Make overuse estimator one dimensional.

webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream_unittest.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 34 matching lines @@
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropOneStreamWrap) {
   CapacityDropTestHelper(1, true, 600);
 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropTwoStreamsWrap) {
   CapacityDropTestHelper(2, true, 700);
 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropThreeStreamsWrap) {
-  CapacityDropTestHelper(3, true, 734);
+  CapacityDropTestHelper(3, true, 567);

[terelius, 2015/10/12 12:04:41]

Use of expected_drop_delta? Reason for change?

[stefan-webrtc, 2015/11/24 16:08:03]

I analyzed this and this is just a matter of timing. In all these test cases
network overuse is detected roughly at the same time, it differs roughly 10-20
ms because all streams don't start at the same time.

This together with the different start time of the streams means that the time
it takes from detection of overuse until the bandwidth estimate finally falls
below 500 kbps (which the test looks for) is a bit different. It turns out that
this case gets a sample almost exactly when it goes below 500 kbps (around 499
kbps), while the others slightly before (around 502-508 kbps).

An important difference is also that all streams are 30 fps, so a single stream
using all bandwidth means that it will only have 30 updates of the BWE per
second, while three streams may get up to 90 updates per second.

I also noted that I accidentally corrected the wrong test here. It should have
been TwoStreams.

 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropThirteenStreamsWrap) {
   CapacityDropTestHelper(13, true, 700);
 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropNineteenStreamsWrap) {
   CapacityDropTestHelper(19, true, 700);
 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, CapacityDropThirtyStreamsWrap) {
   CapacityDropTestHelper(30, true, 700);
 }
 
 TEST_F(RemoteBitrateEstimatorSingleTest, TestTimestampGrouping) {
   TestTimestampGroupingTestHelper();
 }
 }  // namespace webrtc