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

components/sync/test/fake_server/tombstone_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_TEST_FAKE_SERVER_TOMBSTONE_ENTITY_H_
+#define COMPONENTS_SYNC_TEST_FAKE_SERVER_TOMBSTONE_ENTITY_H_
+
+#include <memory>
+#include <string>
+
+#include "components/sync/base/model_type.h"
+#include "components/sync/protocol/sync.pb.h"
+#include "components/sync/test/fake_server/fake_server_entity.h"
+
+namespace fake_server {
+
+// A Sync entity that represents a deleted item.
+class TombstoneEntity : public FakeServerEntity {
+ public:
+  ~TombstoneEntity() override;
+
+  // Factory function for TombstoneEntity.
+  static std::unique_ptr<FakeServerEntity> Create(
+      const std::string& id,
+      const std::string& client_defined_unique_tag);
+
+  // FakeServerEntity implementation.
+  bool RequiresParentId() const override;
+  std::string GetParentId() const override;
+  void SerializeAsProto(sync_pb::SyncEntity* proto) const override;
+  bool IsDeleted() const override;
+
+ private:
+  TombstoneEntity(const std::string& id,
+                  const std::string& client_defined_unique_tag,
+                  const syncer::ModelType& model_type);
+};
+
+}  // namespace fake_server
+
+#endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_TOMBSTONE_ENTITY_H_