Update XPF invariant info to not account for conflation

src/effects/SkArithmeticMode_gpu.h

Index: src/effects/SkArithmeticMode_gpu.h
diff --git a/src/effects/SkArithmeticMode_gpu.h b/src/effects/SkArithmeticMode_gpu.h
index 0c1e9d72f336491f0a4f946dc3876449e6922883..3334e2dce061cc023807b4562710bb6097eaa985 100644
--- a/src/effects/SkArithmeticMode_gpu.h
+++ b/src/effects/SkArithmeticMode_gpu.h
@@ -81,8 +81,8 @@ public:
         return true;
     }
 
-    void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                            GrXPFactory::InvariantOutput*) const override;
+    void getInvariantBlendedColor(const GrProcOptInfo& colorPOI,
+                                  GrXPFactory::InvariantBlendedColor*) const override;
 
 private:
     GrArithmeticXPFactory(float k1, float k2, float k3, float k4, bool enforcePMColor);