Revert of Move DstCopy on gpu into the GrXferProcessor.

src/gpu/gl/builders/GrGLFragmentShaderBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLFragmentShaderBuilder_DEFINED
 #define GrGLFragmentShaderBuilder_DEFINED
 
@@ skipping 79 matching lines @@
 
     // true public interface, defined explicitly in the abstract interfaces above
     bool enableFeature(GLSLFeature) SK_OVERRIDE;
     virtual SkString ensureFSCoords2D(const GrGLProcessor::TransformedCoordsArray& coords,
                                       int index) SK_OVERRIDE;
     const char* fragmentPosition() SK_OVERRIDE;
     const char* dstColor() SK_OVERRIDE;
 
 private:
     // Private public interface, used by GrGLProgramBuilder to build a fragment shader
+    void emitCodeToReadDstTexture();
     void enableCustomOutput();
     void enableSecondaryOutput();
     const char* getPrimaryColorOutputName() const;
     const char* getSecondaryColorOutputName() const;
     bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds) const;
     void bindFragmentShaderLocations(GrGLuint programID);
 
     // As GLProcessors emit code, there are some conditions we need to verify.  We use the below
     // state to track this.  The reset call is called per processor emitted.
     bool hasReadDstColor() const { return fHasReadDstColor; }
@@ skipping 43 matching lines @@
     // the program creator
     bool fHasReadDstColor;
     bool fHasReadFragmentPosition;
 
     friend class GrGLProgramBuilder;
 
     typedef GrGLFPFragmentBuilder INHERITED;
 };
 
 #endif