Make XPFragmentBuilder only Builder with access to DstCopy.

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 72 matching lines @@
         virtual void emitCode(GrGLFPBuilder* builder,
                               const GrFragmentProcessor&,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
                               const TextureSamplerArray&) override {
             if (NULL == inputColor) {
                 inputColor = "vec4(1)";
             }
 
-            GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+            GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
             fsBuilder->codeAppendf("\tfloat luma = dot(vec3(%f, %f, %f), %s.rgb);\n",
                                    SK_ITU_BT709_LUM_COEFF_R,
                                    SK_ITU_BT709_LUM_COEFF_G,
                                    SK_ITU_BT709_LUM_COEFF_B,
                                    inputColor);
             fsBuilder->codeAppendf("\t%s = vec4(0, 0, 0, luma);\n",
                                    outputColor);
 
         }
 
@@ skipping 21 matching lines @@
     GrFragmentProcessor* frag = LumaColorFilterEffect::Create();
     if (frag) {
         if (array) {
             *array->append() = frag;
         }
         return true;
     }
     return false;
 }
 #endif