When updating src/net/base/registry_controlled_domains/effective_tld_names.dat:

1. Obtain the new effective_tld_names.dat, probably by downloading
   http://goo.gl/Ji2bB

2. Remove whitespace from the ends of the lines.
   You could possibly use something like:
     sed -i -e "s/\s*$//g" \
         src/net/base/registry_controlled_domains/effective_tld_names.dat

3. Add the Chromium note back in just after the license at the top, and just
   before '===BEGIN ICANN DOMAINS==='. Ensure there is an empty line above and
   two empty lines below the note. The note should say:
// Chromium note: this is based on Mozilla's file:
//  http://mxr.mozilla.org/mozilla-central/source/netwerk/dns/effective_tld_names.dat?raw=1

4. Build tld_cleanup (the "(net)" > "tld_cleanup" project)

5. Run it (no arguments needed), typically from src/build/Release or
   src/build/Debug. It will re-generate
   src/net/base/registry_controlled_domains/effective_tld_names.gperf.

6. Run gperf on the new effective_tld_names.gperf:
     pushd src/net/base/registry_controlled_domains;
     gperf -a -L "C++" -C -c -o -t -k '*' -NFindDomain -P -K name_offset -D -m 10 \
         effective_tld_names.gperf > effective_tld_names.cc;
     popd;
   It will produce a new effective_tld_names.cc.

7. Check in the updated effective_tld_names.dat, effective_tld_names.gperf,
   and effective_tld_names.cc together.