Detect the situation where we're going to want to do PM/UPM, and want to
use GrConfigConverionEffect, but be unable (due to the lack of a
round-trip pair). This lets us hoist the SW premul work (in
writeSurfacePixels), and avoid all the cascading failure logic in both
functions. (We never try to create the PM/UPM effects unless we know
that they're going to work).
Bug: skia:5853
Change-Id: I0077447cd4be93bba273f8d2826b1ec0f4915c6c
Reviewed-on: https://skia-review.googlesource.com/13592
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
409e74fb2c