SkPaintFilterCanvas skip-draw support

include/utils/SkPaintFilterCanvas.h

Index: include/utils/SkPaintFilterCanvas.h
diff --git a/include/utils/SkPaintFilterCanvas.h b/include/utils/SkPaintFilterCanvas.h
index 0ad7e251b6e54759a850a9c6c04fbbba4d7362db..f2bfaa70e1c54b41bb93a41ff9fba12b9fa444e1 100644
--- a/include/utils/SkPaintFilterCanvas.h
+++ b/include/utils/SkPaintFilterCanvas.h
@@ -48,13 +48,24 @@ public:
 protected:
     /**
      *  Called with the paint that will be used to draw the specified type.
-     *  The implementation may modify the paint as they wish.
+     *  If not null, the implementation may modify the paint as they wish.
      *
-     *  Note: The base implementation calls onFilterPaint() for top-level/explicit paints only.
+     *  The result bool is used to determine whether the draw op is to be
+     *  executed (true) or skipped (false).
+     *
+     *  Note: The base implementation calls onFilter() for top-level/explicit paints only.
      *        To also filter encapsulated paints (e.g. SkPicture, SkTextBlob), clients may need to
      *        override the relevant methods (i.e. drawPicture, drawTextBlob).
      */
-    virtual void onFilterPaint(SkPaint* paint, Type type) const = 0;
+    virtual bool onFilter(SkPaint* paint, Type type) const {
+        if (paint) {

[f(malita), 2016/01/11 19:29:44]

Legacy/transient semantics.  To be converted to a pure virtual after Chromium
gets updated.

+            this->onFilterPaint(paint, type);
+        }
+        return true;
+    }
+
+    // DEPRECATED - do not use
+    virtual void onFilterPaint(SkPaint*, Type) const { }
 
     void onDrawPaint(const SkPaint&) override;
     void onDrawPoints(PointMode, size_t count, const SkPoint pts[], const SkPaint&) override;