Using SQliteAsyncConnection With UnitOfWork & Repository Pattern

i need to implement a fully async architecture for a windows 8 App, i use SQLite For winRT & SQLite.Net in the data layer.

What i have done so far :

DAL

Context :

public interface IContext
    {
        Task InitializeDatabase();
        SQLiteAsyncConnection GetAsyncConnection();
    }

public class SQLiteAsyncContext : IContext
    {
        private SQLiteAsyncConnection _context;
        private String  _dBPath;

        public SQLiteAsyncContext()
        {
            this._dBPath = Path.Combine(
                Windows.Storage.ApplicationData.Current.LocalFolder.Path, "DBName");
            this._context = new SQLiteAsyncConnection(_dBPath);
        }

        public async Task InitializeDatabase()
        {
            await _context.CreateTableAsync<User>();
        }

        public SQLiteAsyncConnection GetAsyncConnection()
        {
            return _context;
        }
    }

Generic Repository :

    public interface IAsyncRepository<T> where T : class
        {
            Task<int> AddAsync(T entity);
            Task<int> UpdateAsync(T entity);
            Task<int> RemoveAsync(T entity);
            Task<IList<T>> GetAllAsync();
            Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate);
            Task SaveChanges();

        }

    public class AsyncRepository<T> : IAsyncRepository<T> where T : class, new()
        {
            private SQLiteAsyncConnection _context;

            public AsyncRepository(IContext _context)
            {
                this._context = _context.GetAsyncConnection();
            }

            public async Task<int> AddAsync(T entity)
            {
                return await _context.InsertAsync(entity);
            }

            public async Task<int> UpdateAsync(T entity)
            {
                return await _context.UpdateAsync(entity);
            }

            public async Task<int> RemoveAsync(T entity)
            {
                return await _context.DeleteAsync(entity);
            }

            public async Task<IList<T>> GetAllAsync()
            {
                return await _context.Table<T>().ToListAsync();
            }

            public async Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
            {
                return await _context.Table<T>().Where(predicate).ToListAsync();
            }
            public Task SaveChanges()
            {
            throw new NotImplementedException();
            }
        }

BL

    public interface IAsyncServices<T> where T : class
    {
        Task<int> AddAsync(T entity);
        Task<int> UpdateAsync(T entity);
        Task<int> RemoveAsync(T entity);
        Task<IList<T>> GetAllAsync();
        Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate);
    }

public class AsyncUserService : IAsyncServices<User>
    {
        private readonly IAsyncRepository<User> _asyncUserRepository;

        public AsyncUserService(IAsyncRepository<User> _asyncUserRepository)
        {
            this._asyncUserRepository = _asyncUserRepository;
        }

        public async Task<int> AddAsync(User entity)
        {
            return await _asyncUserRepository.AddAsync(entity);
        }

        public async Task<int> UpdateAsync(User entity)
        {
            return await _asyncUserRepository.UpdateAsync(entity);
        }

        public async Task<int> RemoveAsync(User entity)
        {
            return await _asyncUserRepository.RemoveAsync(entity);
        }

        public async Task<IList<User>> GetAllAsync()
        {
            return await _asyncUserRepository.GetAllAsync();
        }

        public async Task<IList<User>> GetBy(Expression<Func<User, bool>> predicate)
        {
            return await _asyncUserRepository.GetBy(predicate);
        }
    }

i have some questions :

1. Is it possible to implement UnitOfWork pattern With SQliteAsyncConnection.
2. How To perform Commit & RollBack within Repository.
3. Anything i should Improve ?

Thanks In Advance .