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

src/pdf/SkPDFCanvas.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 SkPDFCanvas_DEFINED
 #define SkPDFCanvas_DEFINED
 
 #include "SkCanvas.h"
 
 class SkPDFDevice;
 
 class SkPDFCanvas : public SkCanvas {
 public:
     SkPDFCanvas(const sk_sp<SkPDFDevice>&);
     ~SkPDFCanvas();
 
 protected:
-    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 onClipRect(const SkRect&, ClipOp, ClipEdgeStyle) override;
+    void onClipRRect(const SkRRect&, ClipOp, ClipEdgeStyle) override;
+    void onClipPath(const SkPath&, ClipOp, ClipEdgeStyle) override;
 
     void onDrawBitmapNine(const SkBitmap&, const SkIRect&, const SkRect&,
                           const SkPaint*) override;
 
     void onDrawImageNine(const SkImage*, const SkIRect&, const SkRect&,
                          const SkPaint*) override;
 
     void onDrawImageRect(const SkImage*,
                          const SkRect*,
                          const SkRect&,
@@ skipping 14 matching lines @@
     void onDrawBitmapLattice(const SkBitmap&,
                              const Lattice&,
                              const SkRect&,
                              const SkPaint*) override;
 
 private:
     typedef SkCanvas INHERITED;
 };
 
 #endif  // SkPDFCanvas_DEFINED