[Sync] Refactor ModelSafeWorker::DoWorkAndWaitUntilDone() to avoid code duplication.

components/sync/engine_impl/directory_update_handler.cc

 // Copyright 2014 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.
 
 #include "components/sync/engine_impl/directory_update_handler.h"
 
 #include <stdint.h>
 
+#include <utility>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
 #include "components/sync/base/data_type_histogram.h"
 #include "components/sync/engine_impl/conflict_resolver.h"
 #include "components/sync/engine_impl/cycle/data_type_debug_info_emitter.h"
 #include "components/sync/engine_impl/cycle/status_controller.h"
 #include "components/sync/engine_impl/update_applicator.h"
 #include "components/sync/syncable/directory.h"
 #include "components/sync/syncable/model_neutral_mutable_entry.h"
@@ skipping 101 matching lines @@
 
 void DirectoryUpdateHandler::ApplyUpdates(StatusController* status) {
   if (IsApplyUpdatesRequired()) {
     // This will invoke handlers that belong to the model and its thread, so we
     // switch to the appropriate thread before we start this work.
     WorkCallback c =
         base::Bind(&DirectoryUpdateHandler::ApplyUpdatesImpl,
                    // We wait until the callback is executed.  We can safely use
                    // Unretained.
                    base::Unretained(this), base::Unretained(status));
-    worker_->DoWorkAndWaitUntilDone(c);
+    worker_->DoWorkAndWaitUntilDone(std::move(c));
 
     debug_info_emitter_->EmitUpdateCountersUpdate();
     debug_info_emitter_->EmitStatusCountersUpdate();
   }
 
   PostApplyUpdates();
 }
 
 void DirectoryUpdateHandler::PassiveApplyUpdates(StatusController* status) {
   if (IsApplyUpdatesRequired()) {
@@ skipping 163 matching lines @@
            new_gc_directive.version_watermark())) {
     ExpireEntriesByVersion(dir_, trans, type_,
                            new_gc_directive.version_watermark());
   }
 
   cached_gc_directive_ =
       base::MakeUnique<sync_pb::GarbageCollectionDirective>(new_gc_directive);
 }
 
 }  // namespace syncer