The development organization (or Development Team if none is available from the development organization)
If the definition of done is part of the conventions, standards or guidelines of the development organization, all Scrum Teams must follow it as a minimum. The Development Team of the Scrum Team can complement it with elements specific for the product or context.
If done for an increment is not a convention of the development organization, the Development Team of the Scrum Team must define a definition of done appropriate for the product.