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

chrome/browser/chromeos/system/automatic_reboot_manager.cc

Index: chrome/browser/chromeos/system/automatic_reboot_manager.cc
diff --git a/chrome/browser/chromeos/system/automatic_reboot_manager.cc b/chrome/browser/chromeos/system/automatic_reboot_manager.cc
index 08f5aacc93f5bdc92d46ca35adc78ad6d16f5a0f..c5359a070bbcca7d8428ebd3b1d60d74fcebc6a6 100644
--- a/chrome/browser/chromeos/system/automatic_reboot_manager.cc
+++ b/chrome/browser/chromeos/system/automatic_reboot_manager.cc
@@ -200,9 +200,8 @@ AutomaticRebootManager::AutomaticRebootManager(
 }
 
 AutomaticRebootManager::~AutomaticRebootManager() {
-  FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
-                    observers_,
-                    WillDestroyAutomaticRebootManager());
+  for (auto& observer : observers_)
+    observer.WillDestroyAutomaticRebootManager();
 
   DBusThreadManager* dbus_thread_manager = DBusThreadManager::Get();
   dbus_thread_manager->GetPowerManagerClient()->RemoveObserver(this);
@@ -384,9 +383,8 @@ void AutomaticRebootManager::RequestReboot() {
   reboot_requested_ = true;
   DCHECK_NE(AutomaticRebootManagerObserver::REBOOT_REASON_UNKNOWN,
             reboot_reason_);
-  FOR_EACH_OBSERVER(AutomaticRebootManagerObserver,
-                    observers_,
-                    OnRebootRequested(reboot_reason_));
+  for (auto& observer : observers_)
+    observer.OnRebootRequested(reboot_reason_);
   MaybeReboot(false);
 }