Reason for revert:
Speculative revert for perf regression (though unlikely).
Original issue's description:
> Rename OpenH264 frame-type conversion function.
>
> 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
>
> Committed: https://crrev.com/39a36705ab734914d500b8a0f214ea630d82ab70
> Cr-Commit-Position: refs/heads/master@{#12636}
TBR=hbos@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=chromium:610347
Review URL: https://codereview.webrtc.org/1964913002 .
Cr-Commit-Position: refs/heads/master@{#12677}
1abf937cec