Specify csharp_namespace in descriptor.proto

src/google/protobuf/descriptor.pb.cc

@@ -755,9 +755,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() {
     "tion\032\206\001\n\010Location\022\020\n\004path\030\001 \003(\005B\002\020\001\022\020\n\004s"
     "pan\030\002 \003(\005B\002\020\001\022\030\n\020leading_comments\030\003 \001(\t\022"
     "\031\n\021trailing_comments\030\004 \001(\t\022!\n\031leading_de"
-    "tached_comments\030\006 \003(\tB;\n\023com.google.prot"
+    "tached_comments\030\006 \003(\tBX\n\023com.google.prot"
     "obufB\020DescriptorProtosH\001Z\ndescriptor\242\002\003G"
-    "PB", 4962);
+    "PB\252\002\032Google.Protobuf.Reflection", 4991);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/descriptor.proto", &protobuf_RegisterTypes);
   FileDescriptorSet::default_instance_ = new FileDescriptorSet();

src/google/protobuf/descriptor.proto

@@ -43,8 +43,7 @@ package google.protobuf;
 option go_package = "descriptor";
 option java_package = "com.google.protobuf";
 option java_outer_classname = "DescriptorProtos";
-// Re-enable this once the tools have picked up the csharp_namespace option.
-// option csharp_namespace = "Google.ProtocolBuffers.DescriptorProtos";
+option csharp_namespace = "Google.Protobuf.Reflection";
 option objc_class_prefix = "GPB";
 
 // descriptor.proto must be optimized for speed because reflection-based