Revert of Move DstCoordTexture to GrXP, rename and remove the word "copy" from dstcopytexture names.

src/gpu/gl/builders/GrGLFragmentShaderBuilder.h

Index: src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
diff --git a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
index 66e55827c032a8e78347a615381cc1a0c001ccca..1ab7af6b1b4e6606fdbd217e79498306f39bdb26 100644
--- a/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
+++ b/src/gpu/gl/builders/GrGLFragmentShaderBuilder.h
@@ -81,10 +81,10 @@
     typedef uint8_t DstReadKey;
     typedef uint8_t FragPosKey;
 
-    /** Returns a key for adding code to read the dst texture color in service of effects that
+    /**  Returns a key for adding code to read the copy-of-dst color in service of effects that
         require reading the dst. It must not return 0 because 0 indicates that there is no dst
-        texture at all (in which case this function should not be called). */
-    static DstReadKey KeyForDstRead(const GrTexture* dsttexture, const GrGLCaps&);
+        copy read at all (in which case this function should not be called). */
+    static DstReadKey KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps&);
 
     /** Returns a key for reading the fragment location. This should only be called if there is an
        effect that will requires the fragment position. If the fragment position is not required,
@@ -149,7 +149,7 @@
         kBottomLeftFragPosRead_FragPosKey   = 0x2,// Read frag pos relative to bottom-left.
     };
 
-    static const char* kDstTextureColorName;
+    static const char* kDstCopyColorName;
 
     bool fHasCustomColorOutput;
     bool fHasSecondaryOutput;