Add WPTs that opus supports both mono and stereo signals.
Currently the first test passes (channelCount:1) but the second test
fails (channelCount:2) because today SDP must be modified to say
"stereo=1".
However the opus spec says that "stereo=1" is just an optional receiver
preference and should not be mandatory to do stereo. Even if it is
missing both mono and stereo should be supported.
The added tests negotiate opus and expect remote track's channel count
to match the local track's channel count in a simple loopback call in
the case that we don't SDP munge.
In a future CL we may want to also test the "stereo=1" SDP munging path
but here we are only concerned with default feature support.
Bug: webrtc:42233792
Change-Id: Ica97b30736d56117b260501e5ccd1c66f2d73fae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5925771
Reviewed-by: Ale Bzk alessiob@chromium.org
Commit-Queue: Henrik Boström hbos@chromium.org
Reviewed-by: Harald Alvestrand hta@chromium.org
Cr-Commit-Position: refs/heads/main@{#1368159}