idleMilliseconds method
The Idle duration in milliseconds.
Throws UnsupportedError when isSupported is false. Implementations
that are supported must not throw for ordinary OS failures — they report
0 (treat the user as active) so a transient failure cannot silently
end monitoring.
Implementation
@override
int idleMilliseconds() {
final nanoseconds = _readIdleNanoseconds();
return idleFromNanoseconds(
succeeded: nanoseconds != null,
nanoseconds: nanoseconds ?? 0,
);
}