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

Review URL: https://codereview.chromium.org/1132093004
diff --git a/src/effects/SkArithmeticMode_gpu.h b/src/effects/SkArithmeticMode_gpu.h
index cbf32ff..0c1e9d7 100644
--- a/src/effects/SkArithmeticMode_gpu.h
+++ b/src/effects/SkArithmeticMode_gpu.h
@@ -90,7 +90,7 @@
     GrXferProcessor* onCreateXferProcessor(const GrCaps& caps,
                                            const GrProcOptInfo& colorPOI,
                                            const GrProcOptInfo& coveragePOI,
-                                           const GrDeviceCoordTexture* dstCopy) const override; 
+                                           const DstTexture*) const override; 
 
     bool willReadDstColor(const GrCaps& caps,
                           const GrProcOptInfo& colorPOI,