This renames I420BufferImpl to JavaI420Buffer and moves it as part of
the API.
Bug: webrtc:7749
Change-Id: I70726f248ba4601b4922996712bdfdafbfa4a1e1
Reviewed-on: https://webrtc-review.googlesource.com/5381
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20145}