Use SkXfermode as public facing enum for GrPorterDuffXP

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 8912851d8f369c88a9b36aeb7d281c8b2490c690..c682838e5612cb47b127c35d72cb0a7b139eb0d1 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -685,7 +685,7 @@ GrTexture* create_mask_GPU(GrContext* context,
         // code path may not be taken. So we use a dst blend coeff of ISA. We
         // could special case AA draws to a dst surface with known alpha=0 to
         // use a zero dst coeff when dual source blending isn't available.
-        tempPaint.setPorterDuffXPFactory(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
+        tempPaint.setPorterDuffXPFactory(SkXfermode::kOne_Coeff, SkXfermode::kISC_Coeff);
     }
 
     // Draw the mask into maskTexture with the path's top-left at the origin using tempPaint.