Reduce usage of FOR_EACH_OBSERVER macro in components/

components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc

Index: components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc
diff --git a/components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc b/components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc
index 806e1be5ac63b9262326bc486fafb0d4c994cce1..d1e85c63235713eddb2cd3fd68d84bb74f0c51c6 100644
--- a/components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc
+++ b/components/proximity_auth/cryptauth/fake_cryptauth_gcm_manager.cc
@@ -36,15 +36,18 @@ void FakeCryptAuthGCMManager::CompleteRegistration(
   registration_in_progress_ = false;
   registration_id_ = registration_id;
   bool success = !registration_id_.empty();
-  FOR_EACH_OBSERVER(Observer, observers_, OnGCMRegistrationResult(success));
+  for (auto& observer : observers_)
+    observer.OnGCMRegistrationResult(success);
 }
 
 void FakeCryptAuthGCMManager::PushReenrollMessage() {
-  FOR_EACH_OBSERVER(Observer, observers_, OnReenrollMessage());
+  for (auto& observer : observers_)
+    observer.OnReenrollMessage();
 }
 
 void FakeCryptAuthGCMManager::PushResyncMessage() {
-  FOR_EACH_OBSERVER(Observer, observers_, OnResyncMessage());
+  for (auto& observer : observers_)
+    observer.OnResyncMessage();
 }
 
 }  // namespace proximity_auth