[Sync] Implements the loopback sync server.

components/sync/engine_impl/loopback_server/persistent_bookmark_entity.h

Index: components/sync/engine_impl/loopback_server/persistent_bookmark_entity.h
diff --git a/components/sync/engine_impl/loopback_server/persistent_bookmark_entity.h b/components/sync/engine_impl/loopback_server/persistent_bookmark_entity.h
new file mode 100644
index 0000000000000000000000000000000000000000..fd629a7ec898f1744764117bcde0e2132b268f66
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+++ b/components/sync/engine_impl/loopback_server/persistent_bookmark_entity.h
@@ -0,0 +1,80 @@
+// 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_BOOKMARK_ENTITY_H_
+#define COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_PERSISTENT_BOOKMARK_ENTITY_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include "components/sync/base/model_type.h"
+#include "components/sync/engine_impl/loopback_server/loopback_server_entity.h"
+#include "components/sync/protocol/sync.pb.h"
+
+namespace syncer {
+
+// A bookmark version of LoopbackServerEntity. This type represents entities
+// that are non-deleted, client-created, and not unique per client account.
+class PersistentBookmarkEntity : public LoopbackServerEntity {
+ public:
+  ~PersistentBookmarkEntity() override;
+
+  // Factory function for PersistentBookmarkEntity. This factory should be used
+  // only for

[pavely, 2016/10/06 23:48:46]

Could you join this line with the next one. The same in comment to next
function.

[pastarmovj, 2016/10/13 14:13:40]

Done.

+  // the first time that a specific bookmark is seen by the server.
+  static std::unique_ptr<LoopbackServerEntity> CreateNew(
+      const sync_pb::SyncEntity& client_entity,
+      const std::string& parent_id,
+      const std::string& client_guid);
+
+  // Factory function for PersistentBookmarkEntity. The server's current entity
+  // for this
+  // ID, |current_server_entity|, is passed here because the client does not
+  // always send the complete entity over the wire. This requires copying of
+  // some of the existing entity when creating a new entity.
+  static std::unique_ptr<LoopbackServerEntity> CreateUpdatedVersion(
+      const sync_pb::SyncEntity& client_entity,
+      const LoopbackServerEntity& current_server_entity,
+      const std::string& parent_id);
+
+  static std::unique_ptr<LoopbackServerEntity> CreateFromEntity(

[pavely, 2016/10/06 23:48:45]

Could you add comment in which scenario this factory method should be used.

[pastarmovj, 2016/10/13 14:13:40]

Done.

+      const sync_pb::SyncEntity& client_entity);
+
+  PersistentBookmarkEntity(const std::string& id,
+                           int64_t version,
+                           const std::string& name,
+                           const std::string& originator_cache_guid,
+                           const std::string& originator_client_item_id,
+                           const sync_pb::UniquePosition& unique_position,
+                           const sync_pb::EntitySpecifics& specifics,
+                           bool is_folder,
+                           const std::string& parent_id,
+                           int64_t creation_time,
+                           int64_t last_modified_time);
+
+  void SetParentId(const std::string& parent_id);
+
+  // LoopbackServerEntity implementation.
+  bool RequiresParentId() const override;
+  std::string GetParentId() const override;
+  void SerializeAsProto(sync_pb::SyncEntity* proto) const override;
+  bool IsFolder() const override;
+
+ private:
+  // All member values have equivalent fields in SyncEntity.
+  std::string originator_cache_guid_;
+  std::string originator_client_item_id_;
+  sync_pb::UniquePosition unique_position_;
+  bool is_folder_;
+  std::string parent_id_;
+  int64_t creation_time_;
+  int64_t last_modified_time_;
+};
+
+}  // namespace syncer
+
+#endif  // COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_PERSISTENT_BOOKMARK_ENTITY_H_