Convert //chrome/browser/extensions from scoped_ptr to std::unique_ptr

chrome/browser/extensions/extension_test_notification_observer.cc

Index: chrome/browser/extensions/extension_test_notification_observer.cc
diff --git a/chrome/browser/extensions/extension_test_notification_observer.cc b/chrome/browser/extensions/extension_test_notification_observer.cc
index f0d2d527123f0214fa776d9307a55e2d2044d09f..4d6c9b0fde64feac2e135291381d0282316ad05a 100644
--- a/chrome/browser/extensions/extension_test_notification_observer.cc
+++ b/chrome/browser/extensions/extension_test_notification_observer.cc
@@ -284,7 +284,7 @@ void ExtensionTestNotificationObserver::WaitForCondition(
       new content::MessageLoopRunner);
   quit_closure_ = runner->QuitClosure();
 
-  scoped_ptr<base::CallbackList<void()>::Subscription> subscription;
+  std::unique_ptr<base::CallbackList<void()>::Subscription> subscription;
   if (notification_set) {
     subscription = notification_set->callback_list().Add(
         base::Bind(&ExtensionTestNotificationObserver::MaybeQuit,