GitLab

This CL fixes two problems with WebView/SkiaRenderer/GL with vulkan hwui:
* Missing allocator, chrome introduced one to use single instance with Skia.
* Wrong fboid for query alpha capabilities.

Bug: 984955
Change-Id: Ib8e9fb57bcf9b11557aac5a412abb91556819038
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2314419Reviewed-by: Peng Huang <penghuang@chromium.org>
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791036}