sync: Implement per-type update processing

sync/tools/testserver/chromiumsync.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """An implementation of the server side of the Chromium sync protocol.
 
 The details of the protocol are described mostly by comments in the protocol
 buffer definition at chrome/browser/sync/protocol/sync.proto.
 """
 
@@ skipping 433 matching lines @@
     """Write the new_timestamp or new_progress_marker fields to a response."""
     if self._original_request.from_progress_marker:
       for data_type, old_timestamp in self._state.iteritems():
         if data_type == TOP_LEVEL:
           continue
         new_marker = sync_pb2.DataTypeProgressMarker()
         new_marker.data_type_id = SyncTypeToProtocolDataTypeId(data_type)
         final_stamp = max(old_timestamp, new_timestamp)
         final_migration = self._migration_history.GetLatestVersion(data_type)
         new_marker.token = pickle.dumps((final_stamp, final_migration))
-        if new_marker not in self._original_request.from_progress_marker:
-          get_updates_response.new_progress_marker.add().MergeFrom(new_marker)
+        get_updates_response.new_progress_marker.add().MergeFrom(new_marker)
     elif self._original_request.HasField('from_timestamp'):
       if self._original_request.from_timestamp < new_timestamp:
         get_updates_response.new_timestamp = new_timestamp
 
 
 class SyncDataModel(object):
   """Models the account state of one sync user."""
   _BATCH_SIZE = 100
 
   # Specify all the permanent items that a model might need.
@@ skipping 1010 matching lines @@
     sending_nigori_node = False
     for entry in entries:
       if entry.name == 'Nigori':
         sending_nigori_node = True
       reply = update_response.entries.add()
       reply.CopyFrom(entry)
     update_sieve.SaveProgress(new_timestamp, update_response)
 
     if update_request.need_encryption_key or sending_nigori_node:
       update_response.encryption_keys.extend(self.account.GetKeystoreKeys())