func BlobKeyForFile(c context.Context, filename string) (appengine.BlobKey, error) {
	req := &blobpb.CreateEncodedGoogleStorageKeyRequest{
		Filename: &filename,
	}
	res := &blobpb.CreateEncodedGoogleStorageKeyResponse{}
	if err := internal.Call(c, "blobstore", "CreateEncodedGoogleStorageKey", req, res); err != nil {
		return "", err
	}
	return appengine.BlobKey(*res.BlobKey), nil
}
func BlobKeyForFile(c context.Context, filename string) (appengine.BlobKey, error) {
	req := &blobpb.CreateEncodedGoogleStorageKeyRequest{
		Filename: &filename,
	}
	res := &blobpb.CreateEncodedGoogleStorageKeyResponse{}
	if err := internal.Call(c, "blobstore", "CreateEncodedGoogleStorageKey", req, res); err != nil {
		return "", err
	}
	return appengine.BlobKey(*res.BlobKey), nil
}
// BlobKeyForFile returns a BlobKey for a Google Storage file.
// The filename should be of the form "/gs/bucket_name/object_name".