Remove TODO saying to remove WebRtcVideoFrame.
Remove TODO saying to remove WebRtcVideoFrame.

Comment was added prematurely, there's no decision to get rid of this
type.

BUG=1788
R=pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/19049004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 432893a1002636aa83f7d356ed8e6f80f908d134

sippet/talk,sippet/talk,sippet/talk,sippet/talk,sippet/talk