Sync FakeServer cleanup: CHECKs and logging info

sync/test/fake_server/permanent_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 SYNC_TEST_FAKE_SERVER_PERMANENT_ENTITY_H_
 #define SYNC_TEST_FAKE_SERVER_PERMANENT_ENTITY_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 13 matching lines @@
   static FakeServerEntity* Create(const syncer::ModelType& model_type,
                                   const std::string& server_tag,
                                   const std::string& name,
                                   const std::string& parent_server_tag);
 
   // Factory function for a top level PermanentEntity. Top level means that the
   // entity's parent is the root entity (no PermanentEntity exists for root).
   static FakeServerEntity* CreateTopLevel(const syncer::ModelType& model_type);
 
   // Factory function for creating an updated version of a PermanentEntity.
-  // This function should only be called for the Nigori entity and will return
-  // NULL if any other type is specified.
+  // This function should only be called for the Nigori entity.
   static FakeServerEntity* CreateUpdatedNigoriEntity(
       const sync_pb::SyncEntity& client_entity,
       FakeServerEntity* current_server_entity);
 
   // FakeServerEntity implementation.
   virtual std::string GetParentId() const OVERRIDE;
   virtual sync_pb::SyncEntity* SerializeAsProto() OVERRIDE;
   virtual bool IsDeleted() const OVERRIDE;
   virtual bool IsFolder() const OVERRIDE;
 
  private:
   PermanentEntity(const std::string& id,
                   const syncer::ModelType& model_type,
                   const std::string& name,
                   const std::string& parent_id,
                   const std::string& server_defined_unique_tag,
                   const sync_pb::EntitySpecifics& entity_specifics);
 
   // All member values have equivalent fields in SyncEntity.
   std::string server_defined_unique_tag_;
   std::string parent_id_;
   sync_pb::EntitySpecifics specifics_;
 };
 
 }  // namespace fake_server
 
 #endif  // SYNC_TEST_FAKE_SERVER_PERMANENT_ENTITY_H_