Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h

Index: third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h
diff --git a/third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h b/third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h
index 426fb3b50f1ae385104f87e624d113588cd55bb0..4079bf7f328e6216d95eb8da12f1dbe0dcaf873f 100644
--- a/third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h
+++ b/third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_options.h
@@ -45,7 +45,8 @@ struct Options {
       file_extension(".cs"),
       base_namespace(""),
       base_namespace_specified(false),
-      internal_access(false) {
+      internal_access(false),
+      legacy_enum_values(false) {
   }
   // Extension of the generated file. Defaults to ".cs"
   string file_extension;
@@ -68,6 +69,12 @@ struct Options {
   // Whether the generated classes should have accessibility level of "internal".
   // Defaults to false that generates "public" classes.
   bool internal_access;
+  // By default, C# codegen now uses PascalCased enum values names, after
+  // removing the enum type name as a prefix (if it *is* a prefix of the value).
+  // Setting this option reverts to the previous behavior of just copying the
+  // value name specified in the .proto file, allowing gradual migration.
+  // This option will be removed before final release.
+  bool legacy_enum_values;
 };
 
 }  // namespace csharp