You can either run this via the Python script, which will start the DevTools frontend in hosted mode automatically.
python scripts/test/run_boot_perf_check.py --chrome-binary=/path/to/Chromium
Or you can run the test via Node, but you will need to launch the server prior.
npm run server
node test/bootperf/bootperf.js --chrome-binary=/path/to/Chromium
If you want to look at the flags for bootperf run it with --help
.