Mark erasure requests as completed after processing is finished.

This intercepts the Ajax responses to personal data eraser page requests, and
monitors the status of a request. Once all of the processing has finished, the
request is marked as completed.

function wp_privacy_process_personal_data_erasure_page( $response, $eraser_index, $email_address, $page, $request_id ) {
	/*
	 * If the eraser response is malformed, don't attempt to consume it; let it
	 * pass through, so that the default Ajax processing will generate a warning
	 * to the user.
	 */
	if ( ! is_array( $response ) ) {
		return $response;
	}

	if ( ! array_key_exists( 'done', $response ) ) {
		return $response;
	}

	if ( ! array_key_exists( 'items_removed', $response ) ) {
		return $response;
	}

	if ( ! array_key_exists( 'items_retained', $response ) ) {
		return $response;
	}

	if ( ! array_key_exists( 'messages', $response ) ) {
		return $response;
	}

	// Get the request.
	$request = wp_get_user_request( $request_id );

	if ( ! $request || 'remove_personal_data' !== $request->action_name ) {
		wp_send_json_error( __( 'Invalid request ID when processing personal data to erase.' ) );
	}

	/** This filter is documented in wp-admin/includes/ajax-actions.php */
	$erasers        = apply_filters( 'wp_privacy_personal_data_erasers', array() );
	$is_last_eraser = count( $erasers ) === $eraser_index;
	$eraser_done    = $response['done'];

	if ( ! $is_last_eraser || ! $eraser_done ) {
		return $response;
	}

	_wp_privacy_completed_request( $request_id );

	/**
	 * Fires immediately after a personal data erasure request has been marked completed.
	 *
	 * @since 4.9.6
	 *
	 * @param int $request_id The privacy request post ID associated with this request.
	 */
	do_action( 'wp_privacy_personal_data_erased', $request_id );

	return $response;
}