We want clients to be able to build their own factories around these
codecs.
Bug: webrtc:7925
Change-Id: Ia8f62d5d85e63ac6e3eb402c5996d8b986625615
Reviewed-on: https://webrtc-review.googlesource.com/c/109529
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Jonathan Yu <yujo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#25543}
