Cleanup: unify rotation to be enum based instead of int for degree.
Cleanup: unify rotation to be enum based instead of int for degree.

Split from https://webrtc-codereview.appspot.com/37029004/

BUG=4145
R=pthatcher@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/37129004

git-svn-id: 03ae4fbe531b1eefc9d815f31e49022782c42458@8257 4adac7df-926f-26a2-2b94-8c16560cd09d

svn2github/webrtc-Revision-8758,svn2github/webrtc-Revision-8758,svn2github/webrtc-Revision-8758,svn2github/webrtc-Revision-8758,svn2github/webrtc-Revision-8758,svn2github/webrtc-Revision-8758