Also removing default case, so if another frame is added to
EVideoFrameType we have to handle it.
This will now NOTREACHED on videoFrameTypeInvalid, but
videoFrameTypeInvalid shouldn't happen if encoding succeeds, so it
should be fine or we should become aware of it.
BUG=
R=hbos@webrtc.org
Review-Url: https://codereview.webrtc.org/1943193003
Cr-Commit-Position: refs/heads/master@{#12636}
39a36705ab