Use profile.sh [-n name] [-f] [-u user] program [args...] to profile an application and record which files are accessed when the application starts.
The -f option runs the program synchronously, necessary for interactive programs (e.g. vim). The -u option specifies which user to run the program as. The -n option allows one to specify the name of the profile, instead of the default which is basename of program.
Use preload.sh [dry] to invoke the preloader. Specifying dry will cause the script to measure the total payload to preload, but without invoking the preloader.
Configure an init-script or systemd service to run the preload.sh script on boot. The preloader is run with nice, ionice, and a big fat target for the kernel's OOM killer, so shouldn't cause any issues besides slowing the boot time somewhat.
If the included do_preload binary is not actually included, or if you are not running on an x64 processor, call ./do_preload.c to compile the preloader binary.
Note that if you want to profile Chromium, you must disable the setuid-sandbox like so:
./profile.sh -f -n chromium chromium --disable-setuid-sandbox