Include necessary WebRTC files and permissions for GeckoView. For
permissions, we need to add the RECORD_AUDIO permission to GeckoView's
AndroidManifest.xml, but since the file is not preprocessed, we can't
use an `#ifdef MOZ_WEBRTC` block, so I think we'll just have to
unconditionally include the permission.

MozReview-Commit-ID: IUd8FFMsW99

--HG--
extra : rebase_source : b75462d53e6bd05b324e8551c888853c8678ec6b