Create fragment processor for performing input color blend with child processor

include/core/SkColorFilter.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkColorFilter_DEFINED
 #define SkColorFilter_DEFINED
 
@@ skipping 118 matching lines @@
      *  array, each of which has been ref'd, so that the caller is responsible for calling unref()
      *  on them when they are finished. If more than one processor is appended, they will be
      *  applied in FIFO order.
      *
      *  The fragment processor(s) must each return their color as a premul normalized value
      *  e.g. each component between [0..1] and each color component <= alpha.
      *
      *  If the subclass returns false, then it should not modify the array at all.
      */
     virtual bool asFragmentProcessors(GrContext*, GrProcessorDataManager*,
-                                      SkTDArray<GrFragmentProcessor*>*) const {
+                                      SkTDArray<const GrFragmentProcessor*>*) const {
         return false;
     }
 
     bool affectsTransparentBlack() const {
         return this->filterColor(0) != 0;
     }
 
     SK_TO_STRING_PUREVIRT()
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
@@ skipping 10 matching lines @@
      *
      *  e.g. compose(filter, compose(compose(filter, filter), filter)) --> 4
      */
     virtual int privateComposedFilterCount() const { return 1; }
     friend class SkComposeColorFilter;
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif