Convert GrClip to an abstract base class

src/gpu/SkGpuDevice.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGpuDevice_DEFINED
 #define SkGpuDevice_DEFINED
 
@@ skipping 135 matching lines @@
                                           const SkMatrix*, const SkPaint*) override;
 
 private:
     // We want these unreffed in DrawContext, RenderTarget, GrContext order.
     SkAutoTUnref<GrContext>         fContext;
     SkAutoTUnref<GrRenderTarget>    fRenderTarget;
     sk_sp<GrDrawContext>            fDrawContext;
 
     SkAutoTUnref<const SkClipStack> fClipStack;
     SkIPoint                        fClipOrigin;
-    GrClip                          fClip;;
+    GrClipStackClip                 fClip;
     // remove when our clients don't rely on accessBitmap()
     SkBitmap                        fLegacyBitmap;
     bool                            fOpaque;
 
     enum Flags {
         kNeedClear_Flag = 1 << 0,  //!< Surface requires an initial clear
         kIsOpaque_Flag  = 1 << 1,  //!< Hint from client that rendering to this device will be
                                    //   opaque even if the config supports alpha.
     };
     static bool CheckAlphaTypeAndGetFlags(const SkImageInfo* info, InitContents init,
@@ skipping 87 matching lines @@
 
     void drawSpriteWithFilter(const SkDraw&, const SkBitmap&, int x, int y,
                               const SkPaint&) override;
 
     friend class GrAtlasTextContext;
     friend class SkSurface_Gpu;      // for access to surfaceProps
     typedef SkBaseDevice INHERITED;
 };
 
 #endif