BlueZ 5.3: Make "Powered" property persistent across reboots.

As part of the daemon shutdown the adapter is powered off. Restarting the
daemon will recover the current status from the adapter, but those will
always show the adapter as powered off. This patch adds a new property to
the "settings" adapter's file storing the last Powered status before
shutdown. This status is restored on startup.

BUG=chromium-os:38832
TEST="restart bluetoothd" preserves the previous powered status.

Change-Id: I63360cf3b4ed0557401d579eef85de07dd23f1ac
Reviewed-on: https://gerrit.chromium.org/gerrit/44986
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
2 files changed