third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_options.h

 // 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 28 matching lines @@
 namespace google {
 namespace protobuf {
 namespace compiler {
 namespace cpp {
 
 // Generator options (see generator.cc for a description of each):
 struct Options {
   Options()
       : safe_boundary_check(false),
         proto_h(false),
+        allow_import_public(true),
         annotate_headers(false),
         enforce_lite(false) {}
 
   string dllexport_decl;
   bool safe_boundary_check;
   bool proto_h;
+  bool allow_import_public;
   bool annotate_headers;
   bool enforce_lite;
   string annotation_pragma_name;
   string annotation_guard_name;
 };
 
 }  // namespace cpp
 }  // namespace compiler
 }  // namespace protobuf
 
 
 }  // namespace google
 #endif  // GOOGLE_PROTOBUF_COMPILER_CPP_OPTIONS_H__