Initial error handling code

include/effects/SkArithmeticMode.h

Index: include/effects/SkArithmeticMode.h
diff --git a/include/effects/SkArithmeticMode.h b/include/effects/SkArithmeticMode.h
index 9de332caef4016e414165549ae07b8eca8de6289..c44290ecfe100c7bbe9f09e7e6d999a81fa67f25 100644
--- a/include/effects/SkArithmeticMode.h
+++ b/include/effects/SkArithmeticMode.h
@@ -11,6 +11,8 @@
 #include "SkXfermode.h"
 
 class SK_API SkArithmeticMode : public SkXfermode {
+    typedef SkXfermode INHERITED;
+
 public:
     /**
      *  result = clamp[k1 * src * dst + k2 * src + k3 * dst + k4]
@@ -25,10 +27,8 @@ public:
     static SkXfermode* Create(SkScalar k1, SkScalar k2,
                               SkScalar k3, SkScalar k4);
 
-    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP();
-
-private:
-    typedef SkXfermode INHERITED;
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_UTILS()
 };
 
 #endif