Remove hack for handling accessibility action on ARC notifications.

ui/message_center/views/custom_notification_view.h

Index: ui/message_center/views/custom_notification_view.h
diff --git a/ui/message_center/views/custom_notification_view.h b/ui/message_center/views/custom_notification_view.h
index 0df481270d7d84eadd42bfcd8e61ad9395b46563..31b7a0d22dc53a15f884e066f10a5add1bc8588b 100644
--- a/ui/message_center/views/custom_notification_view.h
+++ b/ui/message_center/views/custom_notification_view.h
@@ -9,6 +9,10 @@
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/views/message_view.h"
 
+namespace ui {
+struct AXActionData;
+}
+
 namespace views {
 class Painter;
 }
@@ -46,7 +50,7 @@ class MESSAGE_CENTER_EXPORT CustomNotificationView : public MessageView {
   void OnPaint(gfx::Canvas* canvas) override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
   void ChildPreferredSizeChanged(View* child) override;
-  bool OnMousePressed(const ui::MouseEvent& event) override;
+  bool HandleAccessibleAction(const ui::AXActionData& action) override;
 
  private:
   friend class CustomNotificationViewTest;