Make XPFragmentBuilder only Builder with access to DstCopy.

src/effects/SkDisplacementMapEffect.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 "SkDisplacementMapEffect.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 550 matching lines @@
 
     fScaleUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                     kVec2f_GrSLType, kDefault_GrSLPrecision, "Scale");
     const char* scaleUni = builder->getUniformCStr(fScaleUni);
     const char* dColor = "dColor";
     const char* cCoords = "cCoords";
     const char* nearZero = "1e-6"; // Since 6.10352e−5 is the smallest half float, use
                                    // a number smaller than that to approximate 0, but
                                    // leave room for 32-bit float GPU rounding errors.
 
-    GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+    GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
     fsBuilder->codeAppendf("\t\tvec4 %s = ", dColor);
     fsBuilder->appendTextureLookup(samplers[0], coords[0].c_str(), coords[0].getType());
     fsBuilder->codeAppend(";\n");
 
     // Unpremultiply the displacement
     fsBuilder->codeAppendf("\t\t%s.rgb = (%s.a < %s) ? vec3(0.0) : clamp(%s.rgb / %s.a, 0.0, 1.0);",
                            dColor, dColor, nearZero, dColor, dColor);
     SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 1);
     fsBuilder->codeAppendf("\t\tvec2 %s = %s + %s*(%s.",
                            cCoords, coords2D.c_str(), scaleUni, dColor);
@@ skipping 55 matching lines @@
                                        const GrGLSLCaps&, GrProcessorKeyBuilder* b) {
     const GrDisplacementMapEffect& displacementMap = proc.cast<GrDisplacementMapEffect>();
 
     uint32_t xKey = displacementMap.xChannelSelector();
     uint32_t yKey = displacementMap.yChannelSelector() << kChannelSelectorKeyBits;
 
     b->add32(xKey | yKey);
 }
 #endif