abstract name of clipping ops, to transtion to a more restricted set

SkRegion::Op --> SkCanvas::ClipOp (alias) --> SkClipOp

pre-CL needed in chrome : https://codereview.chromium.org/2355583002/

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2355483002

Review-Url: https://codereview.chromium.org/2355483002
diff --git a/src/core/SkLiteDL.h b/src/core/SkLiteDL.h
index 8edd700..b18cc54 100644
--- a/src/core/SkLiteDL.h
+++ b/src/core/SkLiteDL.h
@@ -43,10 +43,10 @@
     void translate(SkScalar, SkScalar);
     void translateZ(SkScalar);
 
-    void clipPath  (const   SkPath&, SkRegion::Op, bool aa);
-    void clipRect  (const   SkRect&, SkRegion::Op, bool aa);
-    void clipRRect (const  SkRRect&, SkRegion::Op, bool aa);
-    void clipRegion(const SkRegion&, SkRegion::Op);
+    void clipPath  (const   SkPath&, SkCanvas::ClipOp, bool aa);
+    void clipRect  (const   SkRect&, SkCanvas::ClipOp, bool aa);
+    void clipRRect (const  SkRRect&, SkCanvas::ClipOp, bool aa);
+    void clipRegion(const SkRegion&, SkCanvas::ClipOp);
 
     void drawPaint (const SkPaint&);
     void drawPath  (const SkPath&, const SkPaint&);