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

src/pipe/SkPipeCanvas.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPipeCanvas_DEFINED
 #define SkPipeCanvas_DEFINED
 
@@ skipping 122 matching lines @@
     void onDrawImageNine(const SkImage*, const SkIRect& center, const SkRect& dst,
                          const SkPaint*) override;
     void onDrawImageLattice(const SkImage*, const Lattice& lattice, const SkRect& dst,
                             const SkPaint*) override;
     void onDrawVertices(VertexMode vmode, int vertexCount,
                               const SkPoint vertices[], const SkPoint texs[],
                               const SkColor colors[], SkXfermode* xmode,
                               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;
 
     // These we turn into images
     void onDrawBitmap(const SkBitmap&, SkScalar left, SkScalar top, const SkPaint*) override;
     void onDrawBitmapRect(const SkBitmap&, const SkRect* src, const SkRect& dst, const SkPaint*,
                           SrcRectConstraint) override;
     void onDrawBitmapNine(const SkBitmap&, const SkIRect& center, const SkRect& dst,
                           const SkPaint*) override;
     void onDrawBitmapLattice(const SkBitmap&, const Lattice& lattice, const SkRect& dst,
                              const SkPaint*) override;
     
 private:
     SkPipeDeduper*  fDeduper;
     SkWStream*      fStream;
 
     friend class SkPipeWriter;
 
     typedef SkCanvas INHERITED;
 };
 
 
 #endif