Add OWNERS file for video_raf module.

R=mlamouri, tguilbert

Bug: 1012063
Change-Id: I863429b989244ebd09db76d0d52b9d8b58053347
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079512
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745572}

third_party/blink/renderer/modules/video_raf/OWNERS

+dalecurtis@chromium.org
+tguilbert@chromium.org