Charge manager: check sanity of charge_full

'charge_full' might be zero or negative if there is something wrong with
battery. Let's check it before using it.

BUG=chrome-os-partner:4153
TEST=Run on a device with charge_full=0. Check charge manager found the
error.

Change-Id: I3948b47a7cb55fd5d333b13fe1525781aeeff2d0
Reviewed-on: https://gerrit.chromium.org/gerrit/29406
Reviewed-by: Jon Salz <jsalz@chromium.org>
Commit-Ready: Vic Yang <victoryang@chromium.org>
Tested-by: Vic Yang <victoryang@chromium.org>
1 file changed