This is reliably killing my local builds after a bit of time after startup:

void MetricsService::PrepareProviderMetricsLogDone(
    std::unique_ptr<MetricsLog::IndependentMetricsLoader> loader,
    bool success) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(independent_loader_active_);
  DCHECK(loader);