[Notifications] Fix swipe to close for ARC notifications.

ui/message_center/views/message_view.cc

Index: ui/message_center/views/message_view.cc
diff --git a/ui/message_center/views/message_view.cc b/ui/message_center/views/message_view.cc
index abc66f3b8fc55ff3168ee48ef34f28686aa2f450..696b847c2653a015b3c2aa71d54dface9f5fcb3d 100644
--- a/ui/message_center/views/message_view.cc
+++ b/ui/message_center/views/message_view.cc
@@ -206,6 +206,11 @@ void MessageView::OnGestureEvent(ui::GestureEvent* event) {
     }
   }
 
+  slide_out_controller_.OnGestureEvent(event);
+  // Do not return here by checking handled(). SlideOutController calls
+  // SetHandled() even though the scroll gesture doesn't make no (or little)
+  // effects on the slide-out behavior. See http://crbug.com/172991
+
   if (!event->IsScrollGestureEvent() && !event->IsFlingScrollEvent())
     return;