Remove usage of FOR_EACH_OBSERVER macro in components/signin

components/signin/core/browser/account_tracker_service.cc

Index: components/signin/core/browser/account_tracker_service.cc
diff --git a/components/signin/core/browser/account_tracker_service.cc b/components/signin/core/browser/account_tracker_service.cc
index 84f522a7eba699f59693d2a541f2a8fb1aaac0ee..efe9e6e36c7c0e53c0bc9135134f88a2eb22c477 100644
--- a/components/signin/core/browser/account_tracker_service.cc
+++ b/components/signin/core/browser/account_tracker_service.cc
@@ -168,20 +168,20 @@ AccountTrackerService::GetMigrationState(const PrefService* pref_service) {
 
 void AccountTrackerService::NotifyAccountUpdated(const AccountState& state) {
   DCHECK(!state.info.gaia.empty());
-  FOR_EACH_OBSERVER(
-      Observer, observer_list_, OnAccountUpdated(state.info));
+  for (auto& observer : observer_list_)
+    observer.OnAccountUpdated(state.info);
 }
 
 void AccountTrackerService::NotifyAccountUpdateFailed(
     const std::string& account_id) {
-  FOR_EACH_OBSERVER(
-      Observer, observer_list_, OnAccountUpdateFailed(account_id));
+  for (auto& observer : observer_list_)
+    observer.OnAccountUpdateFailed(account_id);
 }
 
 void AccountTrackerService::NotifyAccountRemoved(const AccountState& state) {
   DCHECK(!state.info.gaia.empty());
-  FOR_EACH_OBSERVER(
-      Observer, observer_list_, OnAccountRemoved(state.info));
+  for (auto& observer : observer_list_)
+    observer.OnAccountRemoved(state.info);
 }
 
 void AccountTrackerService::StartTrackingAccount(