The purpose is to start splitting out the dependencies to the built-in SW video codecs, so that clients can decide to not depend on them and get a reduction in binary size. Replaces https://webrtc-review.googlesource.com/c/src/+/29101 Bug: webrtc:7925 Change-Id: I46b95aaf42ead70ba78776de60600b8a66a1fe0c Reviewed-on: https://webrtc-review.googlesource.com/33420 Commit-Queue: Anders Carlsson <andersc@webrtc.org> Reviewed-by: Magnus Jedvert <magjed@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21381}