Revert of [sync] Replace FakeServer's implementation with LoopbackServer invocations.

components/sync/engine_impl/loopback_server/persistent_unique_client_entity.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_PERSISTENT_UNIQUE_CLIENT_ENTITY_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_PERSISTENT_UNIQUE_CLIENT_ENTITY_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 21 matching lines @@
                                int64_t version,
                                const std::string& name,
                                const std::string& client_defined_unique_tag,
                                const sync_pb::EntitySpecifics& specifics,
                                int64_t creation_time,
                                int64_t last_modified_time);
 
   ~PersistentUniqueClientEntity() override;
 
   // Factory function for creating a PersistentUniqueClientEntity.
-  static std::unique_ptr<LoopbackServerEntity> CreateFromEntity(
+  static std::unique_ptr<LoopbackServerEntity> Create(
       const sync_pb::SyncEntity& client_entity);
 
-  // Factory function for creating a PersistentUniqueClientEntity for use in the
-  // FakeServer injection API.
-  static std::unique_ptr<LoopbackServerEntity> CreateFromEntitySpecifics(
-      const std::string& name,
-      const sync_pb::EntitySpecifics& entity_specifics);
-
   // Derives an ID from a unique client tagged entity.
   static std::string EffectiveIdForClientTaggedEntity(
       const sync_pb::SyncEntity& entity);
 
   // LoopbackServerEntity implementation.
   bool RequiresParentId() const override;
   std::string GetParentId() const override;
   void SerializeAsProto(sync_pb::SyncEntity* proto) const override;
   sync_pb::LoopbackServerEntity_Type GetLoopbackServerEntityType()
       const override;
 
  private:
   // These member values have equivalent fields in SyncEntity.
   std::string client_defined_unique_tag_;
   int64_t creation_time_;
   int64_t last_modified_time_;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_PERSISTENT_UNIQUE_CLIENT_ENTITY_H_