[sync] Refactor how default sync datatypes are set.

chrome/browser/sync/profile_sync_components_factory_impl.h

 // Copyright (c) 2012 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 CHROME_BROWSER_SYNC_PROFILE_SYNC_COMPONENTS_FACTORY_IMPL_H__
 #define CHROME_BROWSER_SYNC_PROFILE_SYNC_COMPONENTS_FACTORY_IMPL_H__
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 46 matching lines @@
 #endif
   virtual SyncComponents CreateTypedUrlSyncComponents(
       ProfileSyncService* profile_sync_service,
       history::HistoryBackend* history_backend,
       browser_sync::DataTypeErrorHandler* error_handler) OVERRIDE;
   virtual SyncComponents CreateSessionSyncComponents(
       ProfileSyncService* profile_sync_service,
       browser_sync::DataTypeErrorHandler* error_handler) OVERRIDE;
 
  private:
+  // Register data types which are enabled on desktop platforms only.
+  void RegisterDesktopDataTypes(ProfileSyncService* pss);
+  // Register data types which are enabled on both desktop and mobile.
+  void RegisterCommonDataTypes(ProfileSyncService* pss);
+
   Profile* profile_;
   CommandLine* command_line_;
   // Set on the UI thread (since extensions::ExtensionSystemFactory is
   // non-threadsafe); accessed on both the UI and FILE threads in
   // GetSyncableServiceForType.
   extensions::ExtensionSystem* extension_system_;
   scoped_refptr<WebDataService> web_data_service_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncComponentsFactoryImpl);
 };
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_COMPONENTS_FACTORY_IMPL_H__