[Sync] Convert NonBlockingDataTypeController to be single-thread.

components/sync/device_info/device_info_service.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_SERVICE_H_
 #define COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_SERVICE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 162 matching lines @@
   // If |local_device_info_provider_| has initialized.
   bool has_provider_initialized_ = false;
   // If data has been loaded from the store.
   bool has_data_loaded_ = false;
   // if |change_processor()| has been given metadata.
   bool has_metadata_loaded_ = false;
 
   // Used to update our local device info once every pulse interval.
   base::OneShotTimer pulse_timer_;
 
-  // Should always be last member.
-  base::WeakPtrFactory<DeviceInfoService> weak_factory_;
-
   DISALLOW_COPY_AND_ASSIGN(DeviceInfoService);
 };
 
 }  // namespace sync_driver_v2
 
 #endif  // COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_SERVICE_H_