pseudomodem: Refactor Disable

This CL modifies the state machine that manages the disable cycle to use
the new object model.

BUG=chromium-os:37233
TEST=network_3GModemControl/control.pseudomodem,
     1. stop cromo; stop modemmanager
     2. Run /usr/local/autotest/cros/cellular/pseudomodem/pseudomodem.py
     3. Verify that the fake mobile network shows up in the UI.
     4. Manually disable mobile connectivity through the UI.
     5. Verify that mobile connectivity successfully becomes disabled.
     6. Verify that shill hasn't crashed.
     7. Check the pseudomodem output in the console to verify that the
        disable operation proceeded as expected.

Change-Id: I44513e588bf7bc1f2a0a7f6762567aa37a5e09b5
Reviewed-on: https://gerrit.chromium.org/gerrit/40072
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Arman Uguray <armansito@chromium.org>
Commit-Queue: Arman Uguray <armansito@chromium.org>
2 files changed