Create fragment processor for performing input color blend with child processor

src/effects/SkArithmeticMode_gpu.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkArithmeticMode_gpu_DEFINED
 #define SkArithmeticMode_gpu_DEFINED
 
@@ skipping 13 matching lines @@
 class GrTexture;
 
 ///////////////////////////////////////////////////////////////////////////////
 // Fragment Processor
 ///////////////////////////////////////////////////////////////////////////////
 
 class GrGLArtithmeticFP;
 
 class GrArithmeticFP : public GrFragmentProcessor {
 public:
-    static GrFragmentProcessor* Create(GrProcessorDataManager* procDataManager, float k1, float k2,
-                                       float k3, float k4, bool enforcePMColor,
-                                       GrTexture* background) {
-        return new GrArithmeticFP(procDataManager, k1, k2, k3, k4, enforcePMColor, background);
+    static const GrFragmentProcessor* Create(GrProcessorDataManager* procDataManager,
+                                             float k1, float k2, float k3, float k4,
+                                             bool enforcePMColor, const GrFragmentProcessor* dst) {
+        return new GrArithmeticFP(procDataManager, k1, k2, k3, k4, enforcePMColor, dst);
     }
 
     ~GrArithmeticFP() override {};
 
     const char* name() const override { return "Arithmetic"; }
 
     float k1() const { return fK1; }
     float k2() const { return fK2; }
     float k3() const { return fK3; }
     float k4() const { return fK4; }
     bool enforcePMColor() const { return fEnforcePMColor; }
 
 private:
     GrGLFragmentProcessor* onCreateGLInstance() const override;
 
     void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
 
     bool onIsEqual(const GrFragmentProcessor&) const override;
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override;
 
     GrArithmeticFP(GrProcessorDataManager*, float k1, float k2, float k3, float k4,
-                   bool enforcePMColor, GrTexture* background);
+                   bool enforcePMColor, const GrFragmentProcessor* dst);
 
     float                       fK1, fK2, fK3, fK4;
     bool                        fEnforcePMColor;
-    GrCoordTransform            fBackgroundTransform;
-    GrTextureAccess             fBackgroundAccess;
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
     typedef GrFragmentProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 // Xfer Processor
 ///////////////////////////////////////////////////////////////////////////////
 
 class GrArithmeticXPFactory : public GrXPFactory {
@@ skipping 40 matching lines @@
     GR_DECLARE_XP_FACTORY_TEST;
 
     float                       fK1, fK2, fK3, fK4;
     bool                        fEnforcePMColor;
 
     typedef GrXPFactory INHERITED;
 };
 
 #endif
 #endif