in focus/tracing/src/chrome/trace.rs [268:276]
fn relativize_timestamps(events: &mut [Event]) {
if let Some(min) = events.iter().min_by_key(|ev| ev.ts()) {
let min_ts = min.ts();
for ev in events.iter_mut() {
let common = ev.common_mut();
common.ts -= min_ts;
}
}
}