Remove usage of FOR_EACH_OBSERVER macro in components/

components/metrics/metrics_service.cc

Index: components/metrics/metrics_service.cc
diff --git a/components/metrics/metrics_service.cc b/components/metrics/metrics_service.cc
index fb49c5cc6d0a0a7ef3bf31f70246b00c80cabd08..098e20bc1628f3bf099672fd8ebbf9742374ab1b 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -1147,9 +1147,10 @@ void MetricsService::CheckForClonedInstall(
 }
 
 void MetricsService::NotifySyntheticTrialObservers() {
-  FOR_EACH_OBSERVER(variations::SyntheticTrialObserver,
-                    synthetic_trial_observer_list_,
-                    OnSyntheticTrialsChanged(synthetic_trial_groups_));
+  for (variations::SyntheticTrialObserver& observer :
+       synthetic_trial_observer_list_) {
+    observer.OnSyntheticTrialsChanged(synthetic_trial_groups_);
+  }
 }
 
 void MetricsService::GetSyntheticFieldTrialsOlderThan(