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

include/utils/SkNWayCanvas.h

Index: include/utils/SkNWayCanvas.h
diff --git a/include/utils/SkNWayCanvas.h b/include/utils/SkNWayCanvas.h
index 2c93df9aa228a441fa73d547f2bb1c4b9a04dafa..4e7f4224f8c85887397bd44d54b1a4e2e99425fe 100644
--- a/include/utils/SkNWayCanvas.h
+++ b/include/utils/SkNWayCanvas.h
@@ -76,10 +76,10 @@ protected:
                               const uint16_t indices[], int indexCount,
                               const SkPaint&) override;
 
-    void onClipRect(const SkRect&, SkRegion::Op, ClipEdgeStyle) override;
-    void onClipRRect(const SkRRect&, SkRegion::Op, ClipEdgeStyle) override;
-    void onClipPath(const SkPath&, SkRegion::Op, ClipEdgeStyle) override;
-    void onClipRegion(const SkRegion&, SkRegion::Op) override;
+    void onClipRect(const SkRect&, ClipOp, ClipEdgeStyle) override;
+    void onClipRRect(const SkRRect&, ClipOp, ClipEdgeStyle) override;
+    void onClipPath(const SkPath&, ClipOp, ClipEdgeStyle) override;
+    void onClipRegion(const SkRegion&, ClipOp) override;
 
     void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*) override;
     void onDrawAnnotation(const SkRect&, const char[], SkData*) override;