Refactoring of CPU NormalMap handling out into its own class

include/core/SkFlattenable.h

Index: include/core/SkFlattenable.h
diff --git a/include/core/SkFlattenable.h b/include/core/SkFlattenable.h
index 5eabcb3d6d29c0aea2dda585d2155ece4e6ba06a..88aeb7ee38059741b736836ba57885a5ab4b48c2 100644
--- a/include/core/SkFlattenable.h
+++ b/include/core/SkFlattenable.h
@@ -81,7 +81,7 @@ public:
         kSkShader_Type,
         kSkUnused_Type,     // used to be SkUnitMapper
         kSkXfermode_Type,
-        kNormalSource_Type,
+        kSkNormalSource_Type,
     };
 
     typedef sk_sp<SkFlattenable> (*Factory)(SkReadBuffer&);