Add SkNWayCanvas comment API overrides.

include/utils/SkNWayCanvas.h

Index: include/utils/SkNWayCanvas.h
diff --git a/include/utils/SkNWayCanvas.h b/include/utils/SkNWayCanvas.h
index 9d7c4300a6bce36fce381cb16b5f41f6476c564a..5669cd0b2fd73a6d9fb4e194d76572a56b3ab9f9 100644
--- a/include/utils/SkNWayCanvas.h
+++ b/include/utils/SkNWayCanvas.h
@@ -74,6 +74,10 @@ public:
     virtual SkBounder* setBounder(SkBounder*) SK_OVERRIDE;
     virtual SkDrawFilter* setDrawFilter(SkDrawFilter*) SK_OVERRIDE;
 
+    virtual void beginCommentGroup(const char* description) SK_OVERRIDE;
+    virtual void addComment(const char* kywd, const char* value) SK_OVERRIDE;
+    virtual void endCommentGroup() SK_OVERRIDE;
+
 private:
     SkTDArray<SkCanvas*> fList;