Transform DisplayManagerService into a SystemService and start cleaning
up other local services that it uses from window manager and input manager.
Clean up service thread initialization.
Remove unnecessary static variables from ActivityManagerService.
It's starting to become clear that we really need a better way to manage
service dependencies. Boot phases don't quite cut it.
Change-Id: If319dbd7cbfbd4812fe55ece969e818d4b20755b
4ccb823a9f