efl_ui_popup: add timeout signal

Summary: add the timeout signal for user notification

Reviewers: Jaehyun_Cho, jpeg, cedric, Blackmole, thiepha, woohyun

Reviewed By: Jaehyun_Cho

Differential Revision: https://phab.enlightenment.org/D5372

src/lib/elementary/efl_ui_popup.c

@@ -131,6 +131,7 @@ static Eina_Bool
 _timer_cb(void *data)
 {
    Eo *popup = data;
+   efl_event_callback_call(popup, EFL_UI_POPUP_EVENT_TIMEOUT, NULL);
    efl_del(popup);
 
    return ECORE_CALLBACK_CANCEL;

src/lib/elementary/efl_ui_popup.eo

@@ -67,5 +67,6 @@ class Efl.Ui.Popup(Efl.Ui.Layout)
    }
    events {
       bg,clicked; [[This is called whenever the user click background of popup.]]
+      timeout; [[This is called when popup times out.]]
    }
 }