Initial error handling code

include/core/SkXfermode.h

Index: include/core/SkXfermode.h
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 04f3bfe5b6f097db99ddd5049717e66c343db2d1..5061e13886cb0fbb55244f43c9b63a984e0f5b33 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -220,6 +220,8 @@ public:
 
     SkDEVCODE(virtual void toString(SkString* str) const = 0;)
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+    SK_DEFINE_FLATTENABLE_TYPE_CHECKING_PROCS(SkXfermode)
+
 protected:
     SkXfermode(SkFlattenableReadBuffer& rb) : SkFlattenable(rb) {}
 
@@ -240,7 +242,6 @@ private:
 
     friend class SkGraphics;
     static void Term();
-
     typedef SkFlattenable INHERITED;
 };
 
@@ -264,7 +265,7 @@ public:
                         const SkAlpha aa[]) const SK_OVERRIDE;
 
     SK_DEVELOPER_TO_STRING()
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkProcXfermode)
+    SK_DEFINE_FLATTENABLE_DESERIALIZATION_PROCS(SkProcXfermode)
 
 protected:
     SkProcXfermode(SkFlattenableReadBuffer&);