Revert of [Sync] IWYU cleanup.

components/sync/engine_impl/loopback_server/persistent_unique_client_entity.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/loopback_server/persistent_unique_client_entity.h"
 
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+
 #include "base/guid.h"
+#include "components/sync/base/model_type.h"
+#include "components/sync/engine_impl/loopback_server/loopback_server_entity.h"
 #include "components/sync/engine_impl/loopback_server/persistent_permanent_entity.h"
 #include "components/sync/protocol/sync.pb.h"
 #include "components/sync/syncable/syncable_util.h"
 
 using std::string;
 
 using syncer::GetModelTypeFromSpecifics;
 using syncer::ModelType;
 using syncer::syncable::GenerateSyncableHash;
 
@@ skipping 58 matching lines @@
 void PersistentUniqueClientEntity::SerializeAsProto(
     sync_pb::SyncEntity* proto) const {
   LoopbackServerEntity::SerializeBaseProtoFields(proto);
 
   proto->set_client_defined_unique_tag(client_defined_unique_tag_);
   proto->set_ctime(creation_time_);
   proto->set_mtime(last_modified_time_);
 }
 
 }  // namespace syncer