Fix ManyPopupNotifications test with --enable-rich-notifications.

ui/message_center/views/message_popup_collection.h

Index: ui/message_center/views/message_popup_collection.h
diff --git a/ui/message_center/views/message_popup_collection.h b/ui/message_center/views/message_popup_collection.h
index 3bf65681033527c37802f2fede9f7827db9cb8ec..0f71a2fb38974013a25d18d8ab7cebb2f5efdc5e 100644
--- a/ui/message_center/views/message_popup_collection.h
+++ b/ui/message_center/views/message_popup_collection.h
@@ -8,6 +8,7 @@
 #include <list>
 #include <map>
 
+#include "base/gtest_prod_util.h"
 #include "base/timer.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/notification_list.h"
@@ -18,6 +19,10 @@ namespace views {
 class Widget;
 }
 
+namespace ash {
+FORWARD_DECLARE_TEST(WebNotificationTrayTest, ManyPopupNotifications);
+}
+
 namespace message_center {
 
 class ToastContentsView;
@@ -42,6 +47,8 @@ class MESSAGE_CENTER_EXPORT MessagePopupCollection
   void OnMouseExited();
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(ash::WebNotificationTrayTest,
+                           ManyPopupNotifications);
   typedef std::map<std::string, ToastContentsView*> ToastContainer;
 
   void CloseAllWidgets();