public UploadPhotosViewModel(IMediaUploadService uploadService, IAlbumContext albumContext)
{
if (uploadService == null)
throw new ArgumentNullException("uploadService", "picasaController is null.");
if (albumContext == null)
throw new ArgumentNullException("albumContext", "albumContext is null.");
UploadService = uploadService;
_albumContext = albumContext;
Files = new List<string>();
UploadCommand = new UploadPhotoCommand(uploadService);
}