Improves stereo/mono audio support on Android.

Fixes some issues related to calling WebRtcAudioManager.setStereoOutput(true)
and WebRtcAudioManager.setStereoInput(true) and ensures that the ADM reports
correct values related to stereo support given these settings.

Also makes it more clear that the OpenSLES audio implementation does not support
stereo (we now fail in Init()).

To summarize: this change ensures that the user can ask for stereo input
and/or stereo output audio on Android in combination with the Java based
audio layer. By default (if no WebRtcAudioManager.setStereoXXX() APIs are called), mono will be used.


Cr-Original-Commit-Position: refs/heads/master@{#19763}
Cr-Mirrored-Commit: 76535de14fa3d823b30f015d76b535887699dc8f
7 files changed