codegen: InternalMergeFrom

src/google/protobuf/compiler/csharp/csharp_message.cc

diff --git a/src/google/protobuf/compiler/csharp/csharp_message.cc b/src/google/protobuf/compiler/csharp/csharp_message.cc
index 35a3e66..cf00e8c 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message.cc
@@ -640,7 +640,7 @@
   printer->Print("}\n\n");
 
   WriteGeneratedCodeAttributes(printer);
-  printer->Print("public void MergeFrom_Internal(ref pb::ParseContext input) {\n");
+  printer->Print("void pb::IBufferMessage.InternalMergeFrom(ref pb::ParseContext input) {\n");
   printer->Indent();
   printer->Print(
     "uint tag;\n"