Implement Non-Closable Notification

ui/message_center/views/message_center_button_bar.h

Index: ui/message_center/views/message_center_button_bar.h
diff --git a/ui/message_center/views/message_center_button_bar.h b/ui/message_center/views/message_center_button_bar.h
index 74c7b84640513f62c96915c9243030c5d121251a..e7932abd1b5463d0344a9938994ae8810f5cc477 100644
--- a/ui/message_center/views/message_center_button_bar.h
+++ b/ui/message_center/views/message_center_button_bar.h
@@ -7,6 +7,7 @@
 
 #include "base/macros.h"
 #include "build/build_config.h"
+#include "ui/message_center/message_center_export.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/view.h"
@@ -43,6 +44,8 @@ class MessageCenterButtonBar : public views::View,
   // Sometimes we shouldn't see the close-all button.
   void SetCloseAllButtonEnabled(bool enabled);
 
+  MESSAGE_CENTER_EXPORT views::Button* GetCloseAllButtonForTest() const;
+
   // Sometimes we shouldn't see the back arrow (not in settings).
   void SetBackArrowVisible(bool visible);