Add more specialized fragment builders

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
@@ skipping 40 matching lines @@
         fragBuilder->codeAppendf("%s.rgb = min(%s.rgb, %s.a);",
                                  outputColor, outputColor, outputColor);
     }
 }
 
 class GLArithmeticFP : public GrGLSLFragmentProcessor {
 public:
     void emitCode(EmitArgs& args) override {
         const GrArithmeticFP& arith = args.fFp.cast<GrArithmeticFP>();
 
-        GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
         SkString dstColor("dstColor");
         this->emitChild(0, nullptr, &dstColor, args);
 
         fKUni = args.fUniformHandler->addUniform(kFragment_GrShaderFlag,
                                                  kVec4f_GrSLType, kDefault_GrSLPrecision,
                                                  "k");
         const char* kUni = args.fUniformHandler->getUniformCStr(fKUni);
 
         add_arithmetic_code(fragBuilder,
                             args.fInputColor,
@@ skipping 226 matching lines @@
     float k1 = d->fRandom->nextF();
     float k2 = d->fRandom->nextF();
     float k3 = d->fRandom->nextF();
     float k4 = d->fRandom->nextF();
     bool enforcePMColor = d->fRandom->nextBool();
 
     return GrArithmeticXPFactory::Create(k1, k2, k3, k4, enforcePMColor);
 }
 
 #endif