Add explicit |forceOnlineSignin| to user pod status

A user is required to perform an online sign-in against GAIA if his/her
oauth token status is invalid or unknown. Move the logic that makes this
decision from JS to C++. This way, additional conditions that require
online login can be added to the C++ logic without modifying any JS code.

BUG=332081
TEST=Manual

Review URL: https://codereview.chromium.org/140653008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245906 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245906