Adding injectable audio decoder and encoder factory support to the RTCPeerConnection obj-c layer.

Bug: webrtc:8093
Change-Id: I868ce5f75a72c6deb065dec60784289d045ae22a
Reviewed-on: https://chromium-review.googlesource.com/608981
Commit-Queue: Jeremy Newton-Smith <jeremyns@webrtc.org>
Reviewed-by: Zeke Chin <tkchin@webrtc.org>
Reviewed-by: Kári Tristan Helgason <kthelgason@webrtc.org>
Cr-Original-Commit-Position: refs/heads/master@{#19477}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 96de428fd1f301c3ad1355183b45e44db5ef3f7f
10 files changed