retry r235823 with more lax unit test.
Add a timezone utility file to base/.

Currently there's just one function exported, which checks the system timezone and returns a 2-character ASCII country code for it.

BUG=303368
R=isherman@chromium.org
TBR=jshin@chromium.org

Review URL: https://codereview.chromium.org/82973004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237117 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237117