[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 0df481270d7d84eadd42bfcd8e61ad9395b46563..ce9fa41f22589039cfa9416d9ae6020fcf49cfc3 100644
--- a/ui/message_center/views/custom_notification_view.h
+++ b/ui/message_center/views/custom_notification_view.h
@@ -30,13 +30,16 @@ 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;
   bool IsPinned() const override;
   void UpdateControlButtonsVisibility() override;
 
+  // views::SlideOutController::Delegate:
+  void OnSlideChanged() override;
+
   // Overridden from views::View:
   const char* GetClassName() const override;
   gfx::Size GetPreferredSize() const override;