converted Premul / Unpremul to SkSL

Bug: skia:
Change-Id: I4944badbb530e17b9ff7cca389f943e0b5982e01
Reviewed-on: https://skia-review.googlesource.com/72983
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index e283a9f..e584bf5 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -360,6 +360,8 @@
   "$_src/gpu/effects/GrOvalEffect.h",
   "$_src/gpu/effects/GrPorterDuffXferProcessor.cpp",
   "$_src/gpu/effects/GrPorterDuffXferProcessor.h",
+  "$_src/gpu/effects/GrPremulInputFragmentProcessor.cpp",
+  "$_src/gpu/effects/GrPremulInputFragmentProcessor.h",
   "$_src/gpu/effects/GrRectBlurEffect.cpp",
   "$_src/gpu/effects/GrRectBlurEffect.h",
   "$_src/gpu/effects/GrRRectEffect.cpp",
@@ -373,6 +375,8 @@
   "$_src/gpu/effects/GrTextureDomain.cpp",
   "$_src/gpu/effects/GrTextureDomain.h",
   "$_src/gpu/effects/GrTextureStripAtlas.cpp",
+  "$_src/gpu/effects/GrUnpremulInputFragmentProcessor.cpp",
+  "$_src/gpu/effects/GrUnpremulInputFragmentProcessor.h",
   "$_src/gpu/effects/GrXfermodeFragmentProcessor.cpp",
   "$_src/gpu/effects/GrXfermodeFragmentProcessor.h",
   "$_src/gpu/effects/GrYUVEffect.cpp",