Add mixed samples support to XPs

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 3334e2dce061cc023807b4562710bb6097eaa985..17c814477f86d5580a9340f0cf85c1f53d11bfbd 100644
--- a/src/effects/SkArithmeticMode_gpu.h
+++ b/src/effects/SkArithmeticMode_gpu.h
@@ -88,11 +88,13 @@ private:
     GrArithmeticXPFactory(float k1, float k2, float k3, float k4, bool enforcePMColor); 
 
     GrXferProcessor* onCreateXferProcessor(const GrCaps& caps,
+                                           const GrPipelineBuilder&,
                                            const GrProcOptInfo& colorPOI,
                                            const GrProcOptInfo& coveragePOI,
                                            const DstTexture*) const override; 
 
     bool willReadDstColor(const GrCaps& caps,
+                          const GrPipelineBuilder&,
                           const GrProcOptInfo& colorPOI,
                           const GrProcOptInfo& coveragePOI) const override {
         return true;