make_temp_directory:

1. must only be used for per-request connections; and
2. is shared in a clustered environment.

In lib/google/lib.php it is used to set a class config value for the Google_Cache_File class.

At the top of that class, it states:

/*

 * This class implements a basic on disk storage. While that does

 * work quite well it's not the most elegant and scalable solution.

 * It will also get you into a heap of trouble when you try to run

 * this in a clustered environment.

 *

 * @author Chris Chabot <chabotc@google.com>

 */

We should check whether we need this at all, and if we do see if we can use either one of:

1. make_request_directory; or
2. make_localcache_directory; or
3. make_cache_directory.