Make XPFragmentBuilder only Builder with access to DstCopy.

src/effects/SkArithmeticMode_gpu.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticMode_gpu.h"
 
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
 #include "GrProcessor.h"
 #include "GrTexture.h"
 #include "gl/GrGLCaps.h"
 #include "gl/GrGLProcessor.h"
 #include "gl/GrGLProgramDataManager.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 static const bool gUseUnpremul = false;
 
-static void add_arithmetic_code(GrGLFPFragmentBuilder* fsBuilder,
+static void add_arithmetic_code(GrGLFragmentBuilder* fsBuilder,
                                 const char* inputColor,
                                 const char* dstColor,
                                 const char* outputColor,
                                 const char* kUni,
                                 bool enforcePMColor) {
     // We don't try to optimize for this case at all
     if (NULL == inputColor) {
         fsBuilder->codeAppend("const vec4 src = vec4(1);");
     } else {
         fsBuilder->codeAppendf("vec4 src = %s;", inputColor);
@@ skipping 25 matching lines @@
     }
 
     ~GLArithmeticFP() override {}
 
     void emitCode(GrGLFPBuilder* builder,
                   const GrFragmentProcessor& fp,
                   const char* outputColor,
                   const char* inputColor,
                   const TransformedCoordsArray& coords,
                   const TextureSamplerArray& samplers) override {
-        GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+        GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
         fsBuilder->codeAppend("vec4 bgColor = ");
         fsBuilder->appendTextureLookup(samplers[0], coords[0].c_str(), coords[0].getType());
         fsBuilder->codeAppendf(";");
         const char* dstColor = "bgColor";
 
         fKUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                     kVec4f_GrSLType, kDefault_GrSLPrecision,
                                     "k");
         const char* kUni = builder->getUniformCStr(fKUni);
 
@@ skipping 143 matching lines @@
 
     static void GenKey(const GrProcessor& processor, const GrGLSLCaps& caps,
                        GrProcessorKeyBuilder* b) {
         const ArithmeticXP& arith = processor.cast<ArithmeticXP>();
         uint32_t key = arith.enforcePMColor() ? 1 : 0;
         b->add32(key);
     }
 
 private:
     void onEmitCode(const EmitArgs& args) override {
-        GrGLFPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
+        GrGLXPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
 
         const char* dstColor = fsBuilder->dstColor();
 
         fKUni = args.fPB->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                      kVec4f_GrSLType, kDefault_GrSLPrecision,
                                      "k");
         const char* kUni = args.fPB->getUniformCStr(fKUni);
 
         add_arithmetic_code(fsBuilder, args.fInputColor, dstColor, args.fOutputPrimary, kUni, 
                             fEnforcePMColor);
@@ skipping 83 matching lines @@
     float k1 = random->nextF();
     float k2 = random->nextF();
     float k3 = random->nextF();
     float k4 = random->nextF();
     bool enforcePMColor = random->nextBool();
 
     return GrArithmeticXPFactory::Create(k1, k2, k3, k4, enforcePMColor);
 }
 
 #endif