Fold alpha to the draw in savelayer-draw-restore patterns with non-opaque draw
Fold alpha of a save layer call to the subsequent draw call paint, even when
the draw call paint color is already non-opaque.
Comparing the difference of the unoptimized and the optimized call pattern
with all (layer alpha, draw alpha) combinations, this produces
off-by-one pixels ~50% of the time.
Reduces layers of current desk_carsvg.skp (recorded with cross-process
picture image filters allowed) from 122 to 115.
BUG=skia:3119
Review URL: https://codereview.chromium.org/840483005
2 files changed