The Mozilla Toolkit is a set of APIs, built on top of Gecko, which provide advanced services to XUL applications. These services include Profile Management, Chrome Registration, Browsing History, Extension and Theme Management, Application Update Service, and Safe Mode. (More info)
We need to create a telemetry histogram for UPDATER_MAR_DOWNLOAD_SUCCEEDED. It should be a boolean histogram with value 0 when the download verification failed and 1 when the download verification succeeded.