third_party/protobuf: Update to HEAD (f52e188fe4)

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

Index: third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_map_field.h
diff --git a/third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_map_field.h b/third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_map_field.h
index 087dcde0f4eea8476fd63e246468c394d2fec4a5..816687b3a94ee972e5f1881b8028a4803122f1b1 100644
--- a/third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_map_field.h
+++ b/third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_map_field.h
@@ -55,15 +55,20 @@ class MapFieldGenerator : public FieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateSwappingCode(io::Printer* printer) const;
   void GenerateConstructorCode(io::Printer* printer) const;
+  void GenerateCopyConstructorCode(io::Printer* printer) const;
   void GenerateMergeFromCodedStream(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizes(io::Printer* printer) const;
   void GenerateSerializeWithCachedSizesToArray(io::Printer* printer) const;
   void GenerateByteSize(io::Printer* printer) const;
 
  private:
+  // A helper for GenerateSerializeWithCachedSizes{,ToArray}.
+  void GenerateSerializeWithCachedSizes(
+      io::Printer* printer, const std::map<string, string>& variables) const;
+
   const FieldDescriptor* descriptor_;
   const bool dependent_field_;
-  map<string, string> variables_;
+  std::map<string, string> variables_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MapFieldGenerator);
 };