This makes it for future easier conversion for the FFmpeg and Windows WMF decoder, so that we can use their channel map directly.
Also introduce a difference between 2F2 and QUAD, cubeb supports will be added in a future change.
MozReview-Commit-ID: L5NkjeuGslI
Long term goal would be to merge AudioConfig with the existing AudioInfo class which doesn't provide sufficient data to properly determine how to play multichannel audio.
MozReview-Commit-ID: 3UDpZWPBUvS
--HG--
extra : rebase_source : 0643fdba0a6decf4f76c42f40bbb1b237e3e0300