third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/compiler/csharp/csharp_source_generator_base.cc

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
@@ skipping 38 matching lines @@
 
 SourceGeneratorBase::SourceGeneratorBase(const FileDescriptor* descriptor,
                                          const Options *options)
     : descriptor_(descriptor), options_(options) {
 }
 
 SourceGeneratorBase::~SourceGeneratorBase() {
 }
 
 void SourceGeneratorBase::WriteGeneratedCodeAttributes(io::Printer* printer) {
-  // This hook can be used to reintroduce generated code attributes in the future.
+  printer->Print("[global::System.Diagnostics.DebuggerNonUserCodeAttribute]\n");
 }
 
 std::string SourceGeneratorBase::class_access_level() {
   return (IsDescriptorProto(descriptor_) || this->options()->internal_access) ? "internal" : "public";
 }
 
 const Options* SourceGeneratorBase::options() {
   return this->options_;
 }
 
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
 }  // namespace google