Make XPFragmentBuilder only Builder with access to DstCopy.

src/gpu/effects/GrBicubicEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrBicubicEffect.h"
 #include "GrInvariantOutput.h"
 #include "gl/builders/GrGLProgramBuilder.h"
@@ skipping 61 matching lines @@
     SkString cubicBlendName;
 
     static const GrGLShaderVar gCubicBlendArgs[] = {
         GrGLShaderVar("coefficients",  kMat44f_GrSLType),
         GrGLShaderVar("t",             kFloat_GrSLType),
         GrGLShaderVar("c0",            kVec4f_GrSLType),
         GrGLShaderVar("c1",            kVec4f_GrSLType),
         GrGLShaderVar("c2",            kVec4f_GrSLType),
         GrGLShaderVar("c3",            kVec4f_GrSLType),
     };
-    GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+    GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
     SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 0);
     fsBuilder->emitFunction(kVec4f_GrSLType,
                             "cubicBlend",
                             SK_ARRAY_COUNT(gCubicBlendArgs),
                             gCubicBlendArgs,
                             "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
                             "\tvec4 c = coefficients * ts;\n"
                             "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
                             &cubicBlendName);
     fsBuilder->codeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
@@ skipping 125 matching lines @@
             // Use bilerp to handle rotation or fractional translation.
             *filterMode = GrTextureParams::kBilerp_FilterMode;
         }
         return false;
     }
     // When we use the bicubic filtering effect each sample is read from the texture using
     // nearest neighbor sampling.
     *filterMode = GrTextureParams::kNone_FilterMode;
     return true;
 }