Update profiling.md with how to profile chromeos

Change-Id: Ia88a2d25092621de8d63f686ecc096083a7846c0
Reviewed-on: https://chromium-review.googlesource.com/c/1407917
Reviewed-by: Stefan Zager <szager@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622241}
1 file changed