Initial error handling code

src/effects/SkArithmeticMode.cpp

Index: src/effects/SkArithmeticMode.cpp
diff --git a/src/effects/SkArithmeticMode.cpp b/src/effects/SkArithmeticMode.cpp
index d746ecbc3120d0111716d39ba47806177fe1808e..9e250cb5584f8602d435fdf64eed83ed6167e23a 100644
--- a/src/effects/SkArithmeticMode.cpp
+++ b/src/effects/SkArithmeticMode.cpp
@@ -231,6 +231,19 @@ SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
     return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4));
 }
 
+SkFlattenable::Factory SkArithmeticMode::GetFactory(SkFlattenable::Type type) {
+    if (SkFlattenable::kSkArithmeticMode_scalar_Type == type) {
+        return SkArithmeticMode_scalar::CreateProc;
+    }
+    return NULL;
+}
+
+SkFlattenable::TypeCheck SkArithmeticMode::GetTypeCheck(SkFlattenable::Type type) {
+    if (SkFlattenable::kSkArithmeticMode_scalar_Type == type) {
+        return SkArithmeticMode_scalar::IsA;
+    }
+    return NULL;
+}
 
 //////////////////////////////////////////////////////////////////////////////