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

Committed: https://code.google.com/p/webrtc/source/detail?r=8257

Committed: https://code.google.com/p/webrtc/source/detail?r=8276

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

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8277}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0c7ec770ff5be89a875c989f2e99d0c24d0152a7

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