Bluetooth ON/OFF switch may get inconsistent with adapter's state
While investigating a downstream task for Endless, it was noticed that sometimes the Bluetooth ON/OFF switch in gnome-control-center is not representing the correct status of the adapter.
The Bluetooth adapter state can switch between ON and OFF at two different "levels": the rfkill switch or the HCI layer (the later can be changed with hciconfig hci0 up and hciconfig hci0 down). On current master the switch in g-c-c is tracking the adapter status correctly when either of these layers is changed externally, but moving the switch only acts on the rfkill layer. So when turning the adapter OFF with hciconfig, the switch state changes, but later trying to turn it ON with the switch tries to change rfkill which is already unblocked.