GitLab

Also adds comments explaining the implementation of them in
OneCopyRasterBufferProvider.

R=piman@chromium.org, sunnyps@chromium.org

Bug: 730660
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I02a762a4208fcd8d317c35c49f40d36425f27126
Reviewed-on: https://chromium-review.googlesource.com/891442Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532594}