Require a PrefService in startup_metric_utils::RecordBrowserMainMessageLoopStart

components/startup_metric_utils/browser/startup_metric_utils.h

Index: components/startup_metric_utils/browser/startup_metric_utils.h
diff --git a/components/startup_metric_utils/browser/startup_metric_utils.h b/components/startup_metric_utils/browser/startup_metric_utils.h
index cdfb55c99ce50954e40baff65a3183f6f4123a6d..3d373c2a9de060db7767c2341754e0874a54b67d 100644
--- a/components/startup_metric_utils/browser/startup_metric_utils.h
+++ b/components/startup_metric_utils/browser/startup_metric_utils.h
@@ -78,9 +78,7 @@ void RecordExeMainEntryPointTime(const base::Time& time);
 
 // Call this with the time recorded just before the message loop is started.
 // |is_first_run| - is the current launch part of a first run. |pref_service| is
-// an optional parameter which, if provided, will be used to store state for
-// stats that span multiple startups; in its absence those stats will not be
-// recorded.
+// used to store state for stats that span multiple startups.
 void RecordBrowserMainMessageLoopStart(const base::TimeTicks& ticks,
                                        bool is_first_run,
                                        PrefService* pref_service);