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

tests/GrShapeTest.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <initializer_list>
 #include <functional>
 #include "Test.h"
@@ skipping 34 matching lines @@
     // This tolerance is in units of 1/kRes fractions of the bounds width/height.
     static constexpr int kTol = 0;
     GR_STATIC_ASSERT(kRes % 4 == 0);
     SkImageInfo info = SkImageInfo::MakeA8(kRes, kRes);
     sk_sp<SkSurface> surface = SkSurface::MakeRaster(info);
     surface->getCanvas()->clear(0x0);
     SkRect clip = SkRect::MakeXYWH(kRes/4, kRes/4, kRes/2, kRes/2);
     SkMatrix matrix;
     matrix.setRectToRect(bounds, clip, SkMatrix::kFill_ScaleToFit);
     clip.outset(SkIntToScalar(kTol), SkIntToScalar(kTol));
-    surface->getCanvas()->clipRect(clip, SkRegion::kDifference_Op);
+    surface->getCanvas()->clipRect(clip, SkCanvas::kDifference_Op);
     surface->getCanvas()->concat(matrix);
     SkPaint whitePaint;
     whitePaint.setColor(SK_ColorWHITE);
     surface->getCanvas()->drawPath(path, whitePaint);
     SkPixmap pixmap;
     surface->getCanvas()->peekPixels(&pixmap);
 #if defined(SK_BUILD_FOR_WIN)
     // The static constexpr version in #else causes cl.exe to crash.
     const uint8_t* kZeros = reinterpret_cast<uint8_t*>(calloc(kRes, 1));
 #else
@@ skipping 1824 matching lines @@
     test_volatile_path(reporter, PathGeo(SkPath(), PathGeo::Invert::kNo));
 
     test_empty_shape(reporter);
 
     test_lines(reporter);
 
     test_stroked_lines(reporter);
 }
 
 #endif