Use SkXfermode as public facing enum for GrPorterDuffXP

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 6f2b63f5cb2b53977041fef563d89e30be9ead65..cd3ef095b745458c5d1a2ad22cb0a77f4ce5bd42 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -266,15 +266,15 @@ void PorterDuffXferProcessor::calcOutputTypes(GrXferProcessor::OptFlags optFlags
             if (kZero_GrBlendCoeff == fDstBlend) {
                 // write the coverage value to second color
                 fSecondaryOutputType = kCoverage_SecondaryOutputType;
-                fDstBlend = (GrBlendCoeff)GrGpu::kIS2C_GrBlendCoeff;
+                fDstBlend = kIS2C_GrBlendCoeff;
             } else if (kSA_GrBlendCoeff == fDstBlend) {
                 // SA dst coeff becomes 1-(1-SA)*coverage when dst is partially covered.
                 fSecondaryOutputType = kCoverageISA_SecondaryOutputType;
-                fDstBlend = (GrBlendCoeff)GrGpu::kIS2C_GrBlendCoeff;
+                fDstBlend = kIS2C_GrBlendCoeff;
             } else if (kSC_GrBlendCoeff == fDstBlend) {
                 // SA dst coeff becomes 1-(1-SA)*coverage when dst is partially covered.
                 fSecondaryOutputType = kCoverageISC_SecondaryOutputType;
-                fDstBlend = (GrBlendCoeff)GrGpu::kIS2C_GrBlendCoeff;
+                fDstBlend = kIS2C_GrBlendCoeff;
             }
         }
     }
@@ -594,19 +594,30 @@ bool GrPorterDuffXPFactory::willReadDstColor(const GrProcOptInfo& colorPOI,
 
 GR_DEFINE_XP_FACTORY_TEST(GrPorterDuffXPFactory);
 
+
+static bool blend_coeff_refs_src(SkXfermode::Coeff coeff) {
+    return (SkXfermode::kSC_Coeff == coeff || SkXfermode::kISC_Coeff == coeff ||
+            SkXfermode::kSA_Coeff == coeff || SkXfermode::kISA_Coeff == coeff); 
+}
+
+static bool blend_coeff_refs_dst(SkXfermode::Coeff coeff) {
+    return (SkXfermode::kDC_Coeff == coeff || SkXfermode::kIDC_Coeff == coeff ||
+            SkXfermode::kDA_Coeff == coeff || SkXfermode::kIDA_Coeff == coeff); 
+}
+
 GrXPFactory* GrPorterDuffXPFactory::TestCreate(SkRandom* random,
                                                GrContext*,
                                                const GrDrawTargetCaps&,
                                                GrTexture*[]) {
-    GrBlendCoeff src;
+    SkXfermode::Coeff src;
     do {
-        src = GrBlendCoeff(random->nextRangeU(kFirstPublicGrBlendCoeff, kLastPublicGrBlendCoeff));
-    } while (GrBlendCoeffRefsSrc(src));
+        src = SkXfermode::Coeff(random->nextULessThan(SkXfermode::kCoeffCount));
+    } while (blend_coeff_refs_src(src));
 
-    GrBlendCoeff dst;
+    SkXfermode::Coeff dst;
     do {
-        dst = GrBlendCoeff(random->nextRangeU(kFirstPublicGrBlendCoeff, kLastPublicGrBlendCoeff));
-    } while (GrBlendCoeffRefsDst(dst));
+        dst = SkXfermode::Coeff(random->nextULessThan(SkXfermode::kCoeffCount));
+    } while (blend_coeff_refs_dst(dst));
 
     return GrPorterDuffXPFactory::Create(src, dst);
 }