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

src/pipe/SkPipeCanvas.h

Index: src/pipe/SkPipeCanvas.h
diff --git a/src/pipe/SkPipeCanvas.h b/src/pipe/SkPipeCanvas.h
index 82e54fc131c81776855369db188b0aee898b28b7..50d76edfd29f28edbf197873523a5455874b0aa2 100644
--- a/src/pipe/SkPipeCanvas.h
+++ b/src/pipe/SkPipeCanvas.h
@@ -140,10 +140,10 @@ 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;