Use child processors to implement compose color filter.

src/effects/SkColorMatrixFilter.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorMatrixFilter.h"
 #include "SkColorMatrix.h"
 #include "SkColorPriv.h"
@@ skipping 372 matching lines @@
 }
 
 #if SK_SUPPORT_GPU
 #include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
 #include "gl/GrGLFragmentProcessor.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 class ColorMatrixEffect : public GrFragmentProcessor {
 public:
-    static GrFragmentProcessor* Create(const SkColorMatrix& matrix) {
+    static const GrFragmentProcessor* Create(const SkColorMatrix& matrix) {
         return new ColorMatrixEffect(matrix);
     }
 
     const char* name() const override { return "Color Matrix"; }
 
     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
 
     class GLProcessor : public GrGLFragmentProcessor {
     public:
         // this class always generates the same code.
@@ skipping 125 matching lines @@
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(ColorMatrixEffect);
 
 const GrFragmentProcessor* ColorMatrixEffect::TestCreate(GrProcessorTestData* d) {
     SkColorMatrix colorMatrix;
     for (size_t i = 0; i < SK_ARRAY_COUNT(colorMatrix.fMat); ++i) {
         colorMatrix.fMat[i] = d->fRandom->nextSScalar1();
     }
     return ColorMatrixEffect::Create(colorMatrix);
 }
 
-bool SkColorMatrixFilter::asFragmentProcessors(GrContext*, GrProcessorDataManager*,
-                                               SkTDArray<const GrFragmentProcessor*>* array) const {
-    GrFragmentProcessor* frag = ColorMatrixEffect::Create(fMatrix);
-    if (frag) {
-        if (array) {
-            *array->append() = frag;
-        } else {
-            frag->unref();
-            SkDEBUGCODE(frag = nullptr;)
-        }
-        return true;
-    }
-    return false;
+const GrFragmentProcessor* SkColorMatrixFilter::asFragmentProcessor(GrContext*,
+                                                                    GrProcessorDataManager*) const {
+    return ColorMatrixEffect::Create(fMatrix);
 }
 
 #endif
 
 #ifndef SK_IGNORE_TO_STRING
 void SkColorMatrixFilter::toString(SkString* str) const {
     str->append("SkColorMatrixFilter: ");
 
     str->append("matrix: (");
     for (int i = 0; i < 20; ++i) {
         str->appendScalar(fMatrix.fMat[i]);
         if (i < 19) {
             str->append(", ");
         }
     }
     str->append(")");
 }
 #endif