GetWidth and GetHeight (renamed to width and height),
GetNativeHandle (replaced by video_frame_buffer()->native_handle).
TBR=tkchin@webrtc.org (trivial changes to objc RTCVideoFrame and VideoRendererAdapter)
BUG=webrtc:5682
Review-Url: https://codereview.webrtc.org/1990063005
Cr-Commit-Position: refs/heads/master@{#12822}