Update iOS video capture to use non-deprecated APIs.

BUG=3626
R=glaznev@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/17279004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7229 4adac7df-926f-26a2-2b94-8c16560cd09d