GitLab

For SPv175+, don't push mask transparency layer in
BoxPainter::PaintMaskImages() because the layer will be generated
by PaintChunkToCcLayer based on paint properties.

Bug: 771643
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Iadd15bd4234387fe5ecdd248e2b0ca9c5664451f
Reviewed-on: https://chromium-review.googlesource.com/803861
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521153}