This is better in line with Obj-C design guidelines.
BUG=None
Review-Url: https://codereview.webrtc.org/2862493003
Cr-Commit-Position: refs/heads/master@{#18023}
Because the new API doesn't use constraints, refactors settings to instead have a
video resolution setting.
BUG=webrtc:7177
Review-Url: https://codereview.webrtc.org/2778163005
Cr-Commit-Position: refs/heads/master@{#17545}