hbos 9a394f0649 Skip RTCMediaStreamTrackStats.echoReturnLoss[Enhancement] default value.
Due to the Chromium implementation[1] of GetAudioProcesssingStats,
echoReturnLoss and echoReturnLossEnhancement could default to -100 when
no value was available. This should be improved by using rtc::Optional
or AudioProcessorInterface::GetStats being able to return false, but
this requires a bunch of refactoring.

In the meantime we "blacklist" the value -100 which is a nonsense value
anyway. In that case echoReturnLoss[Enhancement] is correctly left
undefined.

[1] https://cs.chromium.org/chromium/src/content/renderer/media/media_stream_audio_processor_options.cc?sq=package:chromium&dr=C&rcl=1481530670&l=461

BUG=chromium:669877

Review-Url: https://codereview.webrtc.org/2573443002
Cr-Commit-Position: refs/heads/master@{#15611}
2016-12-14 15:58:30 +00:00
..
2016-12-02 12:01:21 +00:00
2016-05-15 02:44:18 +00:00
2016-02-10 15:54:53 +00:00
2016-11-23 10:32:14 +00:00