|Change active/inactive state spec.
"active" state means "visible" on source code currently.
But, specification in HMI-FW spec 0.9.2 says it's not visible. https://wiki.automotivelinux.org/hmiframework
It's the right to have resources such as buffers(surface). But from the view point of implementation of windowmanager-service, it is difficult to control resources of application because the buffer is not shared unlike X window system. So fixes just adding the methods to change the state of client.