Details from  issue 828031 :

$ ps aux | grep crashpad_handler | grep -v grep | awk '{print $2}' | xargs -n 1 sudo out/rel/exception_port_tool --show-task --show-bootstrap=com.apple.ReportCrash --pid
service com.apple.ReportCrash 0x1303
task exception port 0, mask 0x3800 (RESOURCE|GUARD|CORPSE_NOTIFY), port 0x1303, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)
service com.apple.ReportCrash 0xc03
task exception port 0, mask 0x1c00 (CRASH|RESOURCE|GUARD), port 0x1203, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)
task exception port 1, mask 0x2000 (CORPSE_NOTIFY), port 0xc03, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)
service com.apple.ReportCrash 0xb03
task exception port 0, mask 0x3800 (RESOURCE|GUARD|CORPSE_NOTIFY), port 0xb03, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)
service com.apple.ReportCrash 0xb03
task exception port 0, mask 0x1c00 (CRASH|RESOURCE|GUARD), port 0x1103, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)
task exception port 1, mask 0x2000 (CORPSE_NOTIFY), port 0xb03, behavior 0x80000003 (STATE_IDENTITY|MACH), flavor 7 (THREAD)

No specific browser test seems to trigger this, but running a lot of browser tests seems to sometimes leave them hanging around.