Optional <TimeDelta> since they may be non existent.

components/page_load_metrics/browser/page_load_metrics_util.cc

Index: components/page_load_metrics/browser/page_load_metrics_util.cc
diff --git a/components/page_load_metrics/browser/page_load_metrics_util.cc b/components/page_load_metrics/browser/page_load_metrics_util.cc
index dbfa35ebad04390d702be6642f8a546ce3715e76..ad4445c859ceba2314c0be89a3785140dfe0789e 100644
--- a/components/page_load_metrics/browser/page_load_metrics_util.cc
+++ b/components/page_load_metrics/browser/page_load_metrics_util.cc
@@ -11,11 +11,19 @@
 
 namespace page_load_metrics {
 
-bool WasStartedInForegroundEventInForeground(base::TimeDelta event,
+bool WasStartedInForegroundEventInForeground(const base::TimeDelta& event,
                                              const PageLoadExtraInfo& info) {
   return info.started_in_foreground && !event.is_zero() &&
-         (info.first_background_time.is_zero() ||
-          event < info.first_background_time);
+         (!info.first_background_time ||
+          event < info.first_background_time.value());
+}
+
+bool WasStartedInForegroundOptionalEventInForeground(
+    const base::Optional<base::TimeDelta>& event,
+    const PageLoadExtraInfo& info) {
+  return info.started_in_foreground && event &&
+         (!info.first_background_time ||
+          event.value() < info.first_background_time.value());
 }
 
 }  // namespace page_load_metrics