Inject current user to OWIN Self-Host Web API 's service

Question

I am using services with business logic in my OWIN Self-Host Web API, and I want to inject current user to this services.

This is my IdentityService with CurrentUser property:

public class IdentityService : IIdentityService
{
    private readonly UserManager<User, int> userManager;

    public IdentityService(UserManager<User, int> userManager)
    {
        if (userManager == null)
        {
            throw new ArgumentNullException("userManager");
        }

        this.userManager = userManager;
    }

    public User CurrentUser
    {
        get
        {
            var identity = Thread.CurrentPrincipal;

            if (identity == null || identity.Identity == null || !identity.Identity.IsAuthenticated)
            {
                if (HttpContext.Current == null || HttpContext.Current.User == null)
                {
                    return null;
                }

                identity = HttpContext.Current.User;
            }

            var user = this.userManager.FindByName(identity.Identity.Name);
            return user;
        }
    }
}

For self-hosted Web API HttpContext.Current is null, so should I check it? Perhaps is better way to determine the current user?