[gnome-contacts] Window: rename overlay to notification_overlay.

[Niels De Graef <nielsdg src gnome org>]

commit 57e9c25d72542968aa3e560b34a653a61a3b742f
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Sat Jan 13 20:30:07 2018 +0100

    Window: rename overlay to notification_overlay.
    
    Then its purpose is immediately clear.

 data/ui/contacts-window.ui |    2 +-
 src/contacts-window.vala   |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/data/ui/contacts-window.ui b/data/ui/contacts-window.ui
index f17b1b4..2f03a50 100644
--- a/data/ui/contacts-window.ui
+++ b/data/ui/contacts-window.ui
@@ -149,7 +149,7 @@
       </object>
     </child>
     <child>
-      <object class="GtkOverlay" id="overlay">
+      <object class="GtkOverlay" id="notification_overlay">
         <property name="visible">True</property>
         <property name="can_focus">False</property>
         <child>
diff --git a/src/contacts-window.vala b/src/contacts-window.vala
index 3b35923..1c45167 100644
--- a/src/contacts-window.vala
+++ b/src/contacts-window.vala
@@ -34,7 +34,7 @@ public class Contacts.Window : Gtk.ApplicationWindow {
   [GtkChild]
   private HeaderBar right_header;
   [GtkChild]
-  private Overlay overlay;
+  private Overlay notification_overlay;
   [GtkChild]
   private Button add_button;
   [GtkChild]
@@ -187,7 +187,7 @@ public class Contacts.Window : Gtk.ApplicationWindow {
   }
 
   public void add_notification (InAppNotification notification) {
-    this.overlay.add_overlay (notification);
+    this.notification_overlay.add_overlay (notification);
     notification.show ();
   }