Add support for split Public Suffix List distinctions.

net/tools/tld_cleanup/README

 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.
+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.exe (the "(net)" > "tld_cleanup" project)
+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 -D -m 5 \
-        effective_tld_names.gperf > effective_tld_names.cc
+         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.