Create fragment processor for performing input color blend with child processor

src/effects/SkLumaColorFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLumaColorFilter.h"
 
 #include "SkColorPriv.h"
@@ skipping 91 matching lines @@
     bool onIsEqual(const GrFragmentProcessor&) const override { return true; }
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
         // The output is always black. The alpha value for the color passed in is arbitrary.
         inout->setToOther(kRGB_GrColorComponentFlags, GrColorPackRGBA(0, 0, 0, 0),
                           GrInvariantOutput::kWill_ReadInput);
     }
 };
 
 bool SkLumaColorFilter::asFragmentProcessors(GrContext*, GrProcessorDataManager*,
-                                             SkTDArray<GrFragmentProcessor*>* array) const {
+                                             SkTDArray<const GrFragmentProcessor*>* array) const {
 
     GrFragmentProcessor* frag = LumaColorFilterEffect::Create();
     if (frag) {
         if (array) {
             *array->append() = frag;
         } else {
             frag->unref();
             SkDEBUGCODE(frag = nullptr;)
         }
         return true;
     }
     return false;
 }
 #endif