Cleanup of webrtc::VideoFrame.
Delete EqualsFrame method, used only by tests. Delete one of the
CreateFrame methods. Drop return value for CreateEmptyFrame, CreateFrame
and CopyFrame.
BUG=webrtc:5426
Committed: https://crrev.com/208019637bfed975f8f13b16d40b90e200763cd6
Cr-Commit-Position: refs/heads/master@{#11783}
R=mflodman@webrtc.org, pbos@webrtc.org, perkj@webrtc.org, pthatcher@webrtc.org
Review URL: https://codereview.webrtc.org/1679323002 .
Cr-Commit-Position: refs/heads/master@{#11811}
739fcb989d