Reland "Revert "Make FP optimizations helpers use SkAlphaType not GrColorType""

This reverts commit 997b37fdb986b45ff9941319b0111b188e749cfc.

Reason for revert: May be blocking Chrome roll

Original change's description:
> Revert "Revert "Make FP optimizations helpers use SkAlphaType not GrColorType""
> 
> This reverts commit 078e8faa26d8b1f33a92e57f587be011150d1776.
> 
> Change-Id: I67b2970584db5a1afbf9928b77c5444947ef71a3
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/255897
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>

TBR=egdaniel@google.com,bsalomon@google.com

Change-Id: I0d2754ac7f4672f0758e4d00cd9e06998637846a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/256196
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrSoftwarePathRenderer.cpp b/src/gpu/GrSoftwarePathRenderer.cpp
index e4ae6c0..4245e9e 100644
--- a/src/gpu/GrSoftwarePathRenderer.cpp
+++ b/src/gpu/GrSoftwarePathRenderer.cpp
@@ -144,6 +144,7 @@
 
 void GrSoftwarePathRenderer::DrawToTargetWithShapeMask(
         sk_sp<GrTextureProxy> proxy,
+        GrColorType srcColorType,
         GrRenderTargetContext* renderTargetContext,
         GrPaint&& paint,
         const GrUserStencilSettings& userStencilSettings,
@@ -165,7 +166,7 @@
                                               SkIntToScalar(-textureOriginInDeviceSpace.fY));
     maskMatrix.preConcat(viewMatrix);
     paint.addCoverageFragmentProcessor(GrSimpleTextureEffect::Make(
-            std::move(proxy), kPremul_SkAlphaType, maskMatrix, GrSamplerState::Filter::kNearest));
+            std::move(proxy), srcColorType, maskMatrix, GrSamplerState::Filter::kNearest));
     DrawNonAARect(renderTargetContext, std::move(paint), userStencilSettings, clip, SkMatrix::I(),
                   dstRect, invert);
 }
@@ -385,9 +386,10 @@
                           *args.fUserStencilSettings, *args.fClip, *args.fViewMatrix, devClipBounds,
                           unclippedDevShapeBounds);
     }
-    DrawToTargetWithShapeMask(std::move(proxy), args.fRenderTargetContext, std::move(args.fPaint),
-                              *args.fUserStencilSettings, *args.fClip, *args.fViewMatrix,
-                              SkIPoint{boundsForMask->fLeft, boundsForMask->fTop}, *boundsForMask);
+    DrawToTargetWithShapeMask(
+            std::move(proxy), GrColorType::kAlpha_8, args.fRenderTargetContext,
+            std::move(args.fPaint), *args.fUserStencilSettings, *args.fClip, *args.fViewMatrix,
+            SkIPoint{boundsForMask->fLeft, boundsForMask->fTop}, *boundsForMask);
 
     return true;
 }