Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/python/google/protobuf/internal/decoder.py

 # 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 624 matching lines @@
         # an end-group tag.
         raise _DecodeError('Unexpected end-group tag.')
       return new_pos
     return DecodeField
 
 
 # --------------------------------------------------------------------
 
 MESSAGE_SET_ITEM_TAG = encoder.TagBytes(1, wire_format.WIRETYPE_START_GROUP)
 
-def MessageSetItemDecoder(descriptor):
+def MessageSetItemDecoder(extensions_by_number):
   """Returns a decoder for a MessageSet item.
 
-  The parameter is the message Descriptor.
+  The parameter is the _extensions_by_number map for the message class.
 
   The message set message looks like this:
     message MessageSet {
       repeated group Item = 1 {
         required int32 type_id = 2;
         required string message = 3;
       }
     }
   """
 
@@ skipping 28 matching lines @@
           raise _DecodeError('Missing group end tag.')
 
     if pos > end:
       raise _DecodeError('Truncated message.')
 
     if type_id == -1:
       raise _DecodeError('MessageSet item missing type_id.')
     if message_start == -1:
       raise _DecodeError('MessageSet item missing message.')
 
-    extension = message.Extensions._FindExtensionByNumber(type_id)
+    extension = extensions_by_number.get(type_id)
     if extension is not None:
       value = field_dict.get(extension)
       if value is None:
         value = field_dict.setdefault(
             extension, extension.message_type._concrete_class())
       if value._InternalParse(buffer, message_start,message_end) != message_end:
         # The only reason _InternalParse would return early is if it encountered
         # an end-group tag.
         raise _DecodeError('Unexpected end-group tag.')
     else:
@@ skipping 137 matching lines @@
         tag (in which case the calling loop should break).
     """
 
     # The wire type is always in the first byte since varints are little-endian.
     wire_type = ord(tag_bytes[0:1]) & wiretype_mask
     return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end)
 
   return SkipField
 
 SkipField = _FieldSkipper()