Convert FWL_ERR into an enum class.

xfa/fwl/core/fwl_error.h

Index: xfa/fwl/core/fwl_error.h
diff --git a/xfa/fwl/core/fwl_error.h b/xfa/fwl/core/fwl_error.h
index 92a483f4e8c34cc5b5ea0e866c8b0883658e57e2..e29f89e012968558bb7f3d3b11343c15c7e82a3a 100644
--- a/xfa/fwl/core/fwl_error.h
+++ b/xfa/fwl/core/fwl_error.h
@@ -7,16 +7,14 @@
 #ifndef XFA_FWL_CORE_FWL_ERROR_H_
 #define XFA_FWL_CORE_FWL_ERROR_H_
 
-#include <stdint.h>
-
-typedef int32_t FWL_ERR;
-
-#define FWL_ERR_Succeeded 0
-#define FWL_ERR_Indefinite -1
-#define FWL_ERR_Parameter_Invalid -100
-#define FWL_ERR_Property_Invalid -200
-#define FWL_ERR_Intermediate_Value__Invalid -300
-#define FWL_ERR_Method_Not_Supported -400
-#define FWL_ERR_Out_Of_Memory -500
+enum class FWL_Error {
+  Succeeded = 0,
+  Indefinite,
+  ParameterInvalid,
+  PropertyInvalid,
+  IntermediateValueInvalid,
+  MethodNotSupported,
+  OutOfMemory
+};
 
 #endif  // XFA_FWL_CORE_FWL_ERROR_H_