There are many different kinds of crashes for Firefox, there is not a single system used to record all of them.

Main process crashes

If the Firefox main process dies, that should be recorded as an aborted session. We would submit a main ping with the reason aborted-session. If we have a crash dump for that crash, we should also submit a crash ping.

The aborted-session information is first written to disk 60 seconds after startup, any earlier crashes will not trigger an aborted-session ping. Also, the aborted-session is updated at least every 5 minutes, so it may lag behind the last session state.

Crashes during startup should be recorded in the next sessions main ping in the STARTUP_CRASH_DETECTED histogram.

Child process crashes

If a Firefox plugin, content, gmplugin, or any other type of child process dies unexpectedly, this is recorded in the main ping’s SUBPROCESS_ABNORMAL_ABORT keyed histogram.

If we catch a crash report for this, then additionally the SUBPROCESS_CRASHES_WITH_DUMP keyed histogram is incremented.

Some processes also generate crash pings when they crash and generate a crash dump. See bug 1352496 for an example of how to allow crash pings for new process types.