These instructions assume you have a full chromiumos checkout at
~/chromiumos/

To generate a schema dump, run this inside the chroot:
  $ lib/cidb_integration_test CIDBMigrationsTest.testMigrations --no-wipe \
       --debug

Note that this will produce some warnings in yellow ("Can't connect to local
MySQL server through socket...") but at the end you should see that it
succeeds, with something like:

   Ran 1 test in 6.163s

   OK

Then, follow the instructions in the developer.readme to re-launch the mysqld
daemon from the temporary directory. Once you have done that, dump the schema
using (again, inside the chroot):

$ mysqldump -u root -S ${tmpdir}/mysqld_dir/mysqld.socket --no-data \
    --single-transaction cidb | grep -v '^--' \
    > ~/trunk/chromite/cidb/schema.dump

Remember to cleanup the temporary directory when you're done.