Implement a test case for firmware developer mode boot.

It handles both Alex/ZGB and others. Since the behavior of these two kinds of
deverloper mode is different. For more details, see the comments in the code.

BUG=chromium-os:19710
TEST=run_remote_tests.sh --remote=$REMOTE_IP -a \
     "servo_vid=0x18d1 servo_pid=0x5001" firmware_DevMode

Change-Id: Ife14a2911cabf9b2711c41e8e2e1a58f7fb71c1e
Reviewed-on: http://gerrit.chromium.org/gerrit/7159
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
2 files changed