Replace FOR_EACH_OBSERVER in c/b/chromeos with range-based for

chrome/browser/chromeos/net/network_portal_detector_impl.cc

Index: chrome/browser/chromeos/net/network_portal_detector_impl.cc
diff --git a/chrome/browser/chromeos/net/network_portal_detector_impl.cc b/chrome/browser/chromeos/net/network_portal_detector_impl.cc
index bb99b868bde721fe7ceca78432789adeb3878cb8..b4691cdd4f7e92e6ed87b1cbacbae275e4599dad 100644
--- a/chrome/browser/chromeos/net/network_portal_detector_impl.cc
+++ b/chrome/browser/chromeos/net/network_portal_detector_impl.cc
@@ -599,8 +599,8 @@ void NetworkPortalDetectorImpl::OnDetectionCompleted(
 void NetworkPortalDetectorImpl::NotifyDetectionCompleted(
     const NetworkState* network,
     const CaptivePortalState& state) {
-  FOR_EACH_OBSERVER(
-      Observer, observers_, OnPortalDetectionCompleted(network, state));
+  for (auto& observer : observers_)
+    observer.OnPortalDetectionCompleted(network, state);
 }
 
 bool NetworkPortalDetectorImpl::AttemptTimeoutIsCancelledForTesting() const {