Adding more assertions.
Fixing utility to actually work when presented with a file based acl instead
of a canonical one.

BUG=None
TEST=None
TBR=djmm

Review URL: http://codereview.chromium.org/2872025

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/gsd_generate_index@51237 0039d316-1c4b-4281-b951-d872f2087c98