[Sync] Implements the loopback sync server.

components/sync/engine_impl/loopback_server/loopback_server_entity.h

Index: components/sync/engine_impl/loopback_server/loopback_server_entity.h
diff --git a/components/sync/test/fake_server/fake_server_entity.h b/components/sync/engine_impl/loopback_server/loopback_server_entity.h
similarity index 66%
copy from components/sync/test/fake_server/fake_server_entity.h
copy to components/sync/engine_impl/loopback_server/loopback_server_entity.h
index 1e0257979822b6ce063df56fa2303f8c5a993488..92b564e4bcf2901a519064da556c3f454e00029f 100644
--- a/components/sync/test/fake_server/fake_server_entity.h
+++ b/components/sync/engine_impl/loopback_server/loopback_server_entity.h
@@ -2,8 +2,8 @@
 // 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_FAKE_SERVER_ENTITY_H_
-#define COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_ENTITY_H_
+#ifndef COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_LOOPBACK_SERVER_ENTITY_H_
+#define COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_LOOPBACK_SERVER_ENTITY_H_
 
 #include <stdint.h>
 
@@ -11,12 +11,13 @@
 #include <string>
 
 #include "components/sync/base/model_type.h"
+#include "components/sync/protocol/loopback_server.pb.h"
 #include "components/sync/protocol/sync.pb.h"
 
-namespace fake_server {
+namespace syncer {
 
-// The representation of a Sync entity for the fake server.
-class FakeServerEntity {
+// The representation of a Sync entity for the loopback server.
+class LoopbackServerEntity {
  public:
   // Creates an ID of the form <type><separator><inner-id> where
   // <type> is the EntitySpecifics field number for |model_type|, <separator>
@@ -30,12 +31,12 @@ class FakeServerEntity {
   // Returns the ID string of the top level node for the specified type.
   static std::string GetTopLevelId(const syncer::ModelType& model_type);
 
-  virtual ~FakeServerEntity();
-  const std::string& id() const { return id_; }
-  const std::string& client_defined_unique_tag() const {
-    return client_defined_unique_tag_;
-  }
-  syncer::ModelType model_type() const { return model_type_; }
+  static std::unique_ptr<LoopbackServerEntity> CreateEntityFromProto(
+      const sync_pb::LoopbackServerEntity& entity);
+
+  virtual ~LoopbackServerEntity();
+  const std::string& GetId() const;
+  syncer::ModelType GetModelType() const;
   int64_t GetVersion() const;
   void SetVersion(int64_t version);
   const std::string& GetName() const;
@@ -44,25 +45,30 @@ class FakeServerEntity {
   // Replaces |specifics_| with |updated_specifics|. This method is meant to be
   // used to mimic a client commit.
   void SetSpecifics(const sync_pb::EntitySpecifics& updated_specifics);
+  sync_pb::EntitySpecifics GetSpecifics() const;
 
   // Common data items needed by server
   virtual bool RequiresParentId() const = 0;
   virtual std::string GetParentId() const = 0;
   virtual void SerializeAsProto(sync_pb::SyncEntity* proto) const = 0;
+  virtual sync_pb::LoopbackServerEntity_Type GetLoopbackServerEntityType()
+      const;
   virtual bool IsDeleted() const;
   virtual bool IsFolder() const;
   virtual bool IsPermanent() const;
 
+  virtual void SerializeAsLoopbackServerEntity(
+      sync_pb::LoopbackServerEntity* entity) const;
+
  protected:
   // Extracts the ModelType from |id|. If |id| is malformed or does not contain
   // a valid ModelType, UNSPECIFIED is returned.
   static syncer::ModelType GetModelTypeFromId(const std::string& id);
 
-  FakeServerEntity(const std::string& id,
-                   const std::string& client_defined_unique_tag,
-                   const syncer::ModelType& model_type,
-                   int64_t version,
-                   const std::string& name);
+  LoopbackServerEntity(const std::string& id,
+                       const syncer::ModelType& model_type,
+                       int64_t version,
+                       const std::string& name);
 
   void SerializeBaseProtoFields(sync_pb::SyncEntity* sync_entity) const;
 
@@ -70,9 +76,6 @@ class FakeServerEntity {
   // The entity's ID.
   const std::string id_;
 
-  // The tag for this entity. Can be empty for bookmarks or permanent entities.
-  const std::string client_defined_unique_tag_;
-
   // The ModelType that categorizes this entity.
   const syncer::ModelType model_type_;
 
@@ -86,6 +89,6 @@ class FakeServerEntity {
   sync_pb::EntitySpecifics specifics_;
 };
 
-}  // namespace fake_server
+}  // namespace syncer
 
-#endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_FAKE_SERVER_ENTITY_H_
+#endif  // COMPONENTS_SYNC_ENGINE_IMPL_LOOPBACK_SERVER_LOOPBACK_SERVER_ENTITY_H_