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

chrome/browser/chromeos/system/pointer_device_observer.cc

Index: chrome/browser/chromeos/system/pointer_device_observer.cc
diff --git a/chrome/browser/chromeos/system/pointer_device_observer.cc b/chrome/browser/chromeos/system/pointer_device_observer.cc
index c15574601370b14f7b80530f774e5f3cd2c1c561..a25aee75656c1e41972b30d505e66ddb7119a341 100644
--- a/chrome/browser/chromeos/system/pointer_device_observer.cc
+++ b/chrome/browser/chromeos/system/pointer_device_observer.cc
@@ -61,11 +61,13 @@ void PointerDeviceObserver::CheckMouseExists() {
 }
 
 void PointerDeviceObserver::OnTouchpadExists(bool exists) {
-  FOR_EACH_OBSERVER(Observer, observers_, TouchpadExists(exists));
+  for (auto& observer : observers_)
+    observer.TouchpadExists(exists);
 }
 
 void PointerDeviceObserver::OnMouseExists(bool exists) {
-  FOR_EACH_OBSERVER(Observer, observers_, MouseExists(exists));
+  for (auto& observer : observers_)
+    observer.MouseExists(exists);
 }
 
 PointerDeviceObserver::Observer::~Observer() {