Warn on missing OVERRIDE/virtual everywhere, not just in header files.

chrome/browser/notifications/notification_browsertest.cc

Index: chrome/browser/notifications/notification_browsertest.cc
diff --git a/chrome/browser/notifications/notification_browsertest.cc b/chrome/browser/notifications/notification_browsertest.cc
index d8a839da13e73973c16b732eaf07fc852a378149..55695c6500cf269076ad3684cb0f94bc678c62d5 100644
--- a/chrome/browser/notifications/notification_browsertest.cc
+++ b/chrome/browser/notifications/notification_browsertest.cc
@@ -102,11 +102,12 @@ class MessageCenterChangeObserver
       const std::string& notification_id) OVERRIDE {
     OnMessageCenterChanged();
   }
-  virtual void OnNotificationRemoved(
-      const std::string& notification_id, bool by_user) {
+  virtual void OnNotificationRemoved(const std::string& notification_id,
+                                     bool by_user) OVERRIDE {
     OnMessageCenterChanged();
   }
-  virtual void OnNotificationUpdated(const std::string& notification_id) {
+  virtual void OnNotificationUpdated(
+      const std::string& notification_id) OVERRIDE {
     OnMessageCenterChanged();
   }