make some canvas utils virtual (for proxy based subclasses)

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 1279 matching lines @@
         SkPaint           fDefaultPaint;
         bool              fDone;
     };
 
     // default impl defers to getDevice()->newSurface(info)
     virtual sk_sp<SkSurface> onNewSurface(const SkImageInfo&, const SkSurfaceProps&);
 
     // default impl defers to its device
     virtual bool onPeekPixels(SkPixmap*);
     virtual bool onAccessTopLayerPixels(SkPixmap*);
+    virtual SkImageInfo onImageInfo() const;
+    virtual bool onGetProps(SkSurfaceProps*) const;
+    virtual void onFlush();
 
     // Subclass save/restore notifiers.
     // Overriders should call the corresponding INHERITED method up the inheritance chain.
     // getSaveLayerStrategy()'s return value may suppress full layer allocation.
     enum SaveLayerStrategy {
         kFullLayer_SaveLayerStrategy,
         kNoLayer_SaveLayerStrategy,
     };
 
     virtual void willSave() {}
@@ skipping 285 matching lines @@
 
 class SkCanvasClipVisitor {
 public:
     virtual ~SkCanvasClipVisitor();
     virtual void clipRect(const SkRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipRRect(const SkRRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) = 0;
 };
 
 #endif