make matrix color filter runtime-only

The unit test Paint_nothingToDraw expects isAlphaUnchanged() to work
correctly on a matrix color filter, so we take care to make it easy
to prove alpha is unchanged when its row is [0 0 0 1 0].

Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Change-Id: I1bc537b2c1c4892bd65831806cf32b933539bff0
Reviewed-by: Brian Osman <>
Commit-Queue: Mike Klein <>
1 file changed