add SkCanvas::drawDRRect

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 3952705c3350b59cbdc51cb0a1e42d5a6d261b01..754fd167a3aae77a9af02f72a3ef79530fe7bb63 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -668,6 +668,12 @@ public:
      */
     virtual void drawRRect(const SkRRect& rrect, const SkPaint& paint);
 
+    /**
+     *  Draw the annulus formed by the outer and inner rrects. The results
+     *  are undefined if the outer does not contain the inner.
+     */
+    void drawDRRect(const SkRRect& outer, const SkRRect& inner, const SkPaint&);
+
     /** Draw the specified circle using the specified paint. If radius is <= 0,
         then nothing will be drawn. The circle will be filled
         or framed based on the Style in the paint.
@@ -1061,6 +1067,8 @@ protected:
     // default impl defers to its device
     virtual const void* onPeekPixels(SkImageInfo*, size_t* rowBytes);
 
+    virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&);
+
     // Returns the canvas to be used by DrawIter. Default implementation
     // returns this. Subclasses that encapsulate an indirect canvas may
     // need to overload this method. The impl must keep track of this, as it