The Device Firmware Update Notification Library provides APIs to be used by device updaters to notify Chrome OS of the current state of the update as it changes.
Include the library package in the ebuild system and use the package config (pc) file to set up the environment.
#include <libdfu_notification/dfu_log_notification.h> ...
DfuLogNotification notification;
notification.StartUpdate("MyCamera"); ... notification.UpdateProgress("MyCamera", 20); ... notification.EndUpdate("MyCamera", true);