[Notifications] Fix swipe to close for 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 6cd7f83a43253832ef8088591495cfeb9f0f9d92..df15b0f157fbd3b65bd4e0c56f6083294ad63e5a 100644
--- a/ui/message_center/views/custom_notification_view.h
+++ b/ui/message_center/views/custom_notification_view.h
@@ -34,12 +34,15 @@ class MESSAGE_CENTER_EXPORT CustomNotificationView : public MessageView {
   void OnContentFocused();
   void OnContentBlured();
 
-  // Overidden from MessageView:
+  // Overridden from MessageView:
   void SetDrawBackgroundAsActive(bool active) override;
   bool IsCloseButtonFocused() const override;
   void RequestFocusOnCloseButton() override;
   void UpdateControlButtonsVisibility() override;
 
+  // views::SlideOutController::Delegate:
+  void OnSlideChanged() override;
+
   // Overridden from views::View:
   const char* GetClassName() const override;
   gfx::Size GetPreferredSize() const override;