Update protobuf to r428, part 1.

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

Index: third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_extension.h
===================================================================
--- third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_extension.h	(revision 216642)
+++ third_party/protobuf/src/google/protobuf/compiler/cpp/cpp_extension.h	(working copy)
@@ -37,6 +37,7 @@
 
 #include <string>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/compiler/cpp/cpp_options.h>
 
 namespace google {
 namespace protobuf {
@@ -56,8 +57,8 @@
 class ExtensionGenerator {
  public:
   // See generator.cc for the meaning of dllexport_decl.
-  explicit ExtensionGenerator(const FieldDescriptor* descriptor,
-                              const string& dllexport_decl);
+  explicit ExtensionGenerator(const FieldDescriptor* desycriptor,
+                              const Options& options);
   ~ExtensionGenerator();
 
   // Header stuff.
@@ -72,7 +73,7 @@
  private:
   const FieldDescriptor* descriptor_;
   string type_traits_;
-  string dllexport_decl_;
+  Options options_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ExtensionGenerator);
 };