getUptimeMs method
Retrieves the monotonic system uptime in milliseconds.
Unlike standard wall-clock time, monotonic uptime is guaranteed to only
increase and is immune to manual user adjustments. The implementation
must include time spent in deep sleep (e.g., elapsedRealtime on Android).
Implementation
Future<int?> getUptimeMs() {
throw UnimplementedError('getUptimeMs() has not been implemented.');
}