Source

File: wp-admin/includes/class-wp-media-list-table.php

protected function get_bulk_actions() {
		$actions = array();
		if ( MEDIA_TRASH ) {
			if ( $this->is_trash ) {
				$actions['untrash'] = __( 'Restore' );
				$actions['delete']  = __( 'Delete permanently' );
			} else {
				$actions['trash'] = __( 'Move to Trash' );
			}
		} else {
			$actions['delete'] = __( 'Delete permanently' );
		}

		if ( $this->detached ) {
			$actions['attach'] = __( 'Attach' );
		}

		return $actions;
	}