Revert of Change SkShader;asFragmentProcessor signature to no longer take skpaint\grcolor*

src/gpu/effects/GrPorterDuffXferProcessor.cpp

Index: src/gpu/effects/GrPorterDuffXferProcessor.cpp
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
index 5f34f75854838a6d419eedcabf366b0dde7586c5..4c9af42cde8d0f56ec5874a50658bee0c15751e0 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -755,7 +755,7 @@
 
 GR_DEFINE_XP_FACTORY_TEST(GrPorterDuffXPFactory);
 
-const GrXPFactory* GrPorterDuffXPFactory::TestCreate(GrProcessorTestData* d) {
+GrXPFactory* GrPorterDuffXPFactory::TestCreate(GrProcessorTestData* d) {
     SkXfermode::Mode mode = SkXfermode::Mode(d->fRandom->nextULessThan(SkXfermode::kLastCoeffMode));
     return GrPorterDuffXPFactory::Create(mode);
 }