Update API for Objective-C RTCPeerConnectionFactory.

BUG=
R=jiayl@webrtc.org, tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1558473002 .

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

Cr-Original-Commit-Position: refs/heads/master@{#11326}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: da99da81c928765ddf4f1ef17f13b9897c3d23b5
9 files changed