Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/compiler/java/java_message.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 74 matching lines @@
 
  protected:
   const Descriptor* descriptor_;
 
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageGenerator);
 };
 
 class ImmutableMessageGenerator : public MessageGenerator {
  public:
-  ImmutableMessageGenerator(const Descriptor* descriptor, Context* context);
+  explicit ImmutableMessageGenerator(const Descriptor* descriptor,
+                                     Context* context);
   virtual ~ImmutableMessageGenerator();
 
   virtual void Generate(io::Printer* printer);
   virtual void GenerateInterface(io::Printer* printer);
   virtual void GenerateExtensionRegistrationCode(io::Printer* printer);
   virtual void GenerateStaticVariables(
       io::Printer* printer, int* bytecode_estimate);
 
   // Returns an estimate of the number of bytes the printed code will compile to
   virtual int GenerateStaticVariableInitializers(io::Printer* printer);
@@ skipping 27 matching lines @@
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ImmutableMessageGenerator);
 };
 
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf
 
 }  // namespace google
 #endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_MESSAGE_H__