* Apparently creating it so early can cause serious breakages
that make StorageManagerService and UsbDeviceManager end up
getting null pointer when trying to get KeyguardManager with
ctx.getSystemService(KeyguardManager.class).
* Moving ctx.getSystemService(KeyguardManager.class) out of
constructor to isKeyguardLocked() solves these issues.
* Also move to getSystemService(Class<T>) while at it.
Change-Id: Ib3f65ba2e726149089ab1fb12030321e0ecdeab1
dee3258356