SkRasterPipelineBlitter simplifications

The main idea here is to simplify, mainly to reduce the number of SkRasterPipeline objects the blitter holds.

  - Use SkBlendMode instead of SkXfermode, just store SkBlendMode.
  - Fuse the shader and color filter together into one SkRasterPipeline
    during blitter creation.
  - I noticed all calls to append_load_d() and append_store() now have the same ctx argument, so I folded that through.

I'll be following up with more of this sort of refactoring... I think I can fold everything into a single SkRasterPipeline during blitter creation now, but I'll want to make sure I've got my ducks in a row for how that works with pipeline strength reduction (like skipping dst loads when drawing in Src mode).

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4021

Change-Id: I88252ab8ad16f102c71bad871f8b6aec2fc1f226
Reviewed-on: https://skia-review.googlesource.com/4021
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

0 files changed, 0 insertions, 0 deletions