Update/move RTCVideoRendererAdapter to webrtc/api/objc.

BUG=
R=tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1533323003 .

Patch from Jon Hjelle <hjon@andyet.net>.

Cr-Original-Commit-Position: refs/heads/master@{#11347}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 891a446a920bb7d51b8d17bae071f44d591ee5e2
5 files changed