Revert switch based variant temporarily.

There are currently some failures caused by this change internally. I'm working
to debug them and hopefully these series of patches should be recommitted by
the end of the week.

Thank you to Micheal Park for the contributions, and for allowing the temporary
rollback.

The commits reverted by this change are:

7d15ece7
e0ec7a02
02197f7e
a175a965