Implement off-the-wire validation scheme for enum types.

ipc/param_traits_log_macros.h

Index: ipc/param_traits_log_macros.h
diff --git a/ipc/param_traits_log_macros.h b/ipc/param_traits_log_macros.h
index 67863ac0e01bddf3cc3fa55941b853abab8d5465..fa50bac68bad7c55c7643f79cff8656f319aa490 100644
--- a/ipc/param_traits_log_macros.h
+++ b/ipc/param_traits_log_macros.h
@@ -11,13 +11,11 @@
 #include "ipc/ipc_message_null_macros.h"
 
 // STRUCT declarations cause corresponding STRUCT_TRAITS declarations to occur.
-#undef IPC_STRUCT_BEGIN
 #undef IPC_STRUCT_BEGIN_WITH_PARENT
 #undef IPC_STRUCT_MEMBER
 #undef IPC_STRUCT_END
 #define IPC_STRUCT_BEGIN_WITH_PARENT(struct_name, parent) \
-  IPC_STRUCT_BEGIN(struct_name)
-#define IPC_STRUCT_BEGIN(struct_name) IPC_STRUCT_TRAITS_BEGIN(struct_name)
+  IPC_STRUCT_TRAITS_BEGIN(struct_name)
 #define IPC_STRUCT_MEMBER(type, name, ...) IPC_STRUCT_TRAITS_MEMBER(name)
 #define IPC_STRUCT_END() IPC_STRUCT_TRAITS_END()
 
@@ -44,8 +42,8 @@
     l->append(")"); \
   }
 
-#undef IPC_ENUM_TRAITS
-#define IPC_ENUM_TRAITS(enum_name) \
+#undef IPC_ENUM_TRAITS_VALIDATE
+#define IPC_ENUM_TRAITS_VALIDATE(enum_name, validation_expression) \
   void ParamTraits<enum_name>::Log(const param_type& p, std::string* l) { \
     LogParam(static_cast<int>(p), l); \
   }