Revert of Revert of Move DstCopy on gpu into the GrXferProcessor.

src/gpu/gl/builders/GrGLProgramBuilder.h

Index: src/gpu/gl/builders/GrGLProgramBuilder.h
diff --git a/src/gpu/gl/builders/GrGLProgramBuilder.h b/src/gpu/gl/builders/GrGLProgramBuilder.h
index 4b40cefad0d681b326a132cf4a2b53e3d45b77b0..a9288cc9b0143898396d3f1f562d6013a29dd259 100644
--- a/src/gpu/gl/builders/GrGLProgramBuilder.h
+++ b/src/gpu/gl/builders/GrGLProgramBuilder.h
@@ -267,11 +267,6 @@
         // We use the render target height to provide a y-down frag coord when specifying
         // origin_upper_left is not supported.
         UniformHandle       fRTHeightUni;
-
-        // Uniforms for computing texture coords to do the dst-copy lookup
-        UniformHandle       fDstCopyTopLeftUni;
-        UniformHandle       fDstCopyScaleUni;
-        UniformHandle       fDstCopySamplerUni;
     };
 
 protected: