[Sync] Have configuration specify which datatypes are ready to sync

chrome/browser/sync/glue/sync_backend_host_impl.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_IMPL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 82 matching lines @@
       syncer::NetworkResources* network_resources) override;
   void UpdateCredentials(const syncer::SyncCredentials& credentials) override;
   void StartSyncingWithServer() override;
   void SetEncryptionPassphrase(const std::string& passphrase,
                                bool is_explicit) override;
   bool SetDecryptionPassphrase(const std::string& passphrase) override
       WARN_UNUSED_RESULT;
   void StopSyncingForShutdown() override;
   scoped_ptr<base::Thread> Shutdown(syncer::ShutdownReason reason) override;
   void UnregisterInvalidationIds() override;
-  void ConfigureDataTypes(
+  syncer::ModelTypeSet ConfigureDataTypes(
       syncer::ConfigureReason reason,
       const DataTypeConfigStateMap& config_state_map,
       const base::Callback<void(syncer::ModelTypeSet, syncer::ModelTypeSet)>&
           ready_task,
       const base::Callback<void()>& retry_callback) override;
   void ActivateDataType(
       syncer::ModelType type,
       syncer::ModelSafeGroup group,
       sync_driver::ChangeProcessor* change_processor) override;
   void DeactivateDataType(syncer::ModelType type) override;
@@ skipping 243 matching lines @@
 
   base::WeakPtrFactory<SyncBackendHostImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHostImpl);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_IMPL_H_