Add a performance test script / "performance regression tests"

[jhasse]

Currently this is done manually by building Chromium before and after a commit. I think it would be good to have a script, which you can pass two commit hashes and a path to a Chromium source, which will then compare the -d stats result.

Maybe add the functionality to misc/measure.py?

See #1577 (comment)

[nightlark]

How long does it take to build chromium?

[ClausKlein]

use ccache, that helps ...

[scivision]

Would it be useful to have smaller but also ubiquitous packages? Maybe in Fortran too, like Lapack that is a couple thousand files mostly in Fortran.
Typically for benchmarking one tries to do several repeated runs to mitigate unpredictable externally-driven slowdowns.
Maybe look to the packages Phoronix frequently uses for build benchmarking?