Add onGetBlendInfo to GrXferProcessor

src/effects/SkArithmeticMode_gpu.cpp

Index: src/effects/SkArithmeticMode_gpu.cpp
diff --git a/src/effects/SkArithmeticMode_gpu.cpp b/src/effects/SkArithmeticMode_gpu.cpp
index cd5f09a4e33bb4bb4f5a812549aa398164acb391..46c5b0f75a9b04441347900e34282b29038381f4 100644
--- a/src/effects/SkArithmeticMode_gpu.cpp
+++ b/src/effects/SkArithmeticMode_gpu.cpp
@@ -181,12 +181,6 @@ public:
                                                GrColor* overrideColor,
                                                const GrDrawTargetCaps& caps) override;
 
-    void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const override {
-        blendInfo->fSrcBlend = kOne_GrBlendCoeff;
-        blendInfo->fDstBlend = kZero_GrBlendCoeff;
-        blendInfo->fBlendConstant = 0;
-    }
-
     float k1() const { return fK1; }
     float k2() const { return fK2; }
     float k3() const { return fK3; }