cromo: Crash during suspend_stress_test due to invalid access in
GobiModem::OnResumed

The GobiModem destructor did not unregister certain callbacks from the
CromoServer, which caused an OnResumed callback to get called on a
dealloc'd GobiModem instance. This CL adds code to unregister all of the
callbacks that were registered with CromoServer during GobiModem::Init.

BUG=chromium-os:35046
TEST=Ran cromo with valgrind along with /usr/bin/suspend_stress_test
repeatedly overnight for two days. Crash occurred many times during the
first run, but did not occur again after the patch.

Change-Id: Id24c963eff60729436ef21fa740f835dd1d458d3
Reviewed-on: https://gerrit.chromium.org/gerrit/34701
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Arman Uguray <armansito@chromium.org>
Tested-by: Arman Uguray <armansito@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/35580
1 file changed