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/SkGpuDevice_drawTexture.cpp b/src/gpu/SkGpuDevice_drawTexture.cpp
index c3b3649..ce5c49b 100644
--- a/src/gpu/SkGpuDevice_drawTexture.cpp
+++ b/src/gpu/SkGpuDevice_drawTexture.cpp
@@ -220,15 +220,14 @@
         SkPoint srcQuad[4];
         GrMapRectPoints(dstRect, srcRect, dstClip, srcQuad, 4);
 
-        rtc->drawTextureQuad(clip, std::move(proxy), srcColorInfo.colorType(),
-                             srcColorInfo.alphaType(), filter, paint.getBlendMode(), color, srcQuad,
-                             dstClip, aa, aaFlags,
+        rtc->drawTextureQuad(clip, std::move(proxy), srcColorInfo.colorType(), filter,
+                             paint.getBlendMode(), color, srcQuad, dstClip, aa, aaFlags,
                              constraint == SkCanvas::kStrict_SrcRectConstraint ? &srcRect : nullptr,
                              ctm, std::move(textureXform));
     } else {
-        rtc->drawTexture(clip, std::move(proxy), srcColorInfo.colorType(), srcColorInfo.alphaType(),
-                         filter, paint.getBlendMode(), color, srcRect, dstRect, aa, aaFlags,
-                         constraint, ctm, std::move(textureXform));
+        rtc->drawTexture(clip, std::move(proxy), srcColorInfo.colorType(), filter,
+                         paint.getBlendMode(), color, srcRect, dstRect, aa, aaFlags, constraint,
+                         ctm, std::move(textureXform));
     }
 }
 
@@ -556,7 +555,7 @@
         GrSurfaceOrigin origin = proxy->origin();
         const GrSwizzle& swizzle = proxy->textureSwizzle();
         textures[i].fProxyView = {std::move(proxy), origin, swizzle};
-        textures[i].fSrcAlphaType = image->alphaType();
+        textures[i].fSrcColorType = SkColorTypeToGrColorType(image->colorType());
         textures[i].fSrcRect = set[i].fSrcRect;
         textures[i].fDstRect = set[i].fDstRect;
         textures[i].fDstClipQuad = clip;