[Sync] Pass ModelTypeSet by value everywhere

sync/engine/sync_scheduler.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.
 //
 // A class to schedule syncer tasks intelligently.
 #ifndef SYNC_ENGINE_SYNC_SCHEDULER_H_
 #define SYNC_ENGINE_SYNC_SCHEDULER_H_
 
 #include <string>
 
@@ skipping 11 matching lines @@
 }  // namespace tracked_objects
 
 namespace syncer {
 
 struct ServerConnectionEvent;
 
 struct ConfigurationParams {
   ConfigurationParams();
   ConfigurationParams(
       const sync_pb::GetUpdatesCallerInfo::GetUpdatesSource& source,
-      const ModelTypeSet& types_to_download,
+      ModelTypeSet types_to_download,
       const ModelSafeRoutingInfo& routing_info,
       const base::Closure& ready_task);
   ~ConfigurationParams();
 
   // Source for the configuration.
   sync_pb::GetUpdatesCallerInfo::GetUpdatesSource source;
   // The types that should be downloaded.
   ModelTypeSet types_to_download;
   // The new routing info (superset of types to be downloaded).
   ModelSafeRoutingInfo routing_info;
@@ skipping 60 matching lines @@
   // Called when credentials are updated by the user.
   virtual void OnCredentialsUpdated() = 0;
 
   // Called when the network layer detects a connection status change.
   virtual void OnConnectionStatusChange() = 0;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_SCHEDULER_H_