Introduce new GLScaler (API only) to replace GLHelper+GLHelperScaler.

Introduces the "outer shell" API to for GLScaler, with upcoming patches
coming soon to fill-in the rest of the implementation. This is a major
refactoring of GLHelper+GLHelperScaler to: 1) fix dangerous memory
management issues, 2) provide a cleaner interface for client-side code,
3) unblock performance and color management efforts.

Bug: 870036,758057
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: Ib8f0ed9b988bfe914bd8983940b089262543e8c7
Reviewed-on: https://chromium-review.googlesource.com/1194783
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Reviewed-by: Xiangjun Zhang <xjz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589674}
5 files changed