[Sync] Refactor non-frontend DTC to handle new API properly.

chrome/browser/prefs/pref_service.h

 // Copyright (c) 2011 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.
 
 // This provides a way to access the application's current preferences.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #pragma once
 
@@ skipping 273 matching lines @@
   base::DictionaryValue* GetPreferenceValues() const;
 
   // A helper method to quickly look up a preference.  Returns NULL if the
   // preference is not registered.
   const Preference* FindPreference(const char* pref_name) const;
 
   bool ReadOnly() const;
 
   // SyncableService getter.
   // TODO(zea): Have PrefService implement SyncableService directly.
-  SyncableService* GetSyncableService();
+  PrefModelAssociator* GetSyncableService();
 
  protected:
   // Construct a new pref service, specifying the pref sources as explicit
   // PrefStore pointers. This constructor is what CreatePrefService() ends up
   // calling. It's also used for unit tests.
   PrefService(PrefStore* managed_platform_prefs,
               PrefStore* managed_cloud_prefs,
               PrefStore* extension_prefs,
               PrefStore* command_line_prefs,
               PersistentPrefStore* user_prefs,
@@ skipping 85 matching lines @@
   // of registered preferences are.
   mutable PreferenceSet prefs_;
 
   // The model associator that maintains the links with the sync db.
   scoped_ptr<PrefModelAssociator> pref_sync_associator_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_H_