chromeos: Load chaps module and lookup TPM slots on the worker pool.

BUG=345713

Review URL: https://codereview.chromium.org/181053002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253942 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253942