Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/src/google/protobuf/compiler/plugin.h

Index: third_party/protobuf/src/google/protobuf/compiler/plugin.h
diff --git a/third_party/protobuf/src/google/protobuf/compiler/plugin.h b/third_party/protobuf/src/google/protobuf/compiler/plugin.h
index 679f9bdb8b7cc41f3ae1c76f7169dbb888043fae..d2793a9ff13b2409a1a668fd49fdf467fb47132f 100644
--- a/third_party/protobuf/src/google/protobuf/compiler/plugin.h
+++ b/third_party/protobuf/src/google/protobuf/compiler/plugin.h
@@ -40,6 +40,13 @@
 //   }
 // You must link your plugin against libprotobuf and libprotoc.
 //
+// The core part of PluginMain is to invoke the given CodeGenerator on a
+// CodeGeneratorRequest to generate a CodeGeneratorResponse. This part is
+// abstracted out and made into function GenerateCode so that it can be reused,
+// for example, to implement a variant of PluginMain that does some
+// preprocessing on the input CodeGeneratorRequest before feeding the request
+// to the given code generator.
+//
 // To get protoc to use the plugin, do one of the following:
 // * Place the plugin binary somewhere in the PATH and give it the name
 //   "protoc-gen-NAME" (replacing "NAME" with the name of your plugin).  If you
@@ -55,16 +62,27 @@
 #ifndef GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__
 #define GOOGLE_PROTOBUF_COMPILER_PLUGIN_H__
 
+#include <string>
+
 #include <google/protobuf/stubs/common.h>
 namespace google {
 namespace protobuf {
 namespace compiler {
 
 class CodeGenerator;    // code_generator.h
+class CodeGeneratorRequest;
+class CodeGeneratorResponse;
 
 // Implements main() for a protoc plugin exposing the given code generator.
 LIBPROTOC_EXPORT int PluginMain(int argc, char* argv[], const CodeGenerator* generator);
 
+// Generates code using the given code generator. Returns true if the code
+// generation is successful. If the code geneartion fails, error_msg may be
+// populated to describe the failure cause.
+bool GenerateCode(const CodeGeneratorRequest& request,
+    const CodeGenerator& generator, CodeGeneratorResponse* response,
+    string* error_msg);
+
 }  // namespace compiler
 }  // namespace protobuf