* alexa_domains.list

  The Alexa top 10k domains, one per line, constructed by running
  make_alexa_top_list.py.  Used as an input to make_top_domain_gperf.
  It's derived from
   src/tools/perf/page_sets/alexa1-10000-urls.json with make_alexa_top_list.py

* alexa_domains.skeletons

  The checked-in output of make_top_domain_skeletons.  Processed during the
  build to generate alexa_domains-trie-inc.cc, which is used by
  url_formatter.cc.  This must be regenerated as follows if ICU is updated,
  since skeletons can differ across ICU versions:

  $ ninja -C $build_outdir make_top_domain_skeletons
  $ $build_outdir/make_top_domain_skeletons

* test_domains.list
  A list of domains to use in IDNToUnicode test instead of the actual
  top domain list. Manually edited to match what's in IDNToUnicode test.

* test_domains.skeletons
  Generated output of test_domains.list along with alexa_domains.skeletons
  by make_top_domain_skeletons.
