Fix the check to distinguish accessibility events.

ui/arc/notification/arc_custom_notification_view.cc

Index: ui/arc/notification/arc_custom_notification_view.cc
diff --git a/ui/arc/notification/arc_custom_notification_view.cc b/ui/arc/notification/arc_custom_notification_view.cc
index d640556c32c2f29ddc19f24d7f48010a9cb6f930..4a2f6b4832c68c897ce816001898946087f09f01 100644
--- a/ui/arc/notification/arc_custom_notification_view.cc
+++ b/ui/arc/notification/arc_custom_notification_view.cc
@@ -555,7 +555,7 @@ bool ArcCustomNotificationView::OnMousePressed(const ui::MouseEvent& event) {
   // means the event is generated by automation API.
   if (event.IsOnlyLeftMouseButton() &&
       item_->expand_state() != mojom::ArcNotificationExpandState::FIXED_SIZE &&
-      event.target() != surface_->window()) {
+      event.target() == nullptr) {

[yoshiki, 2017/04/05 08:55:51]

Could you update the comment above and mention about the logic of the null
check?

     item_->ToggleExpansion();
     return true;
   }