[gnome-usage] header-bar: Make it a HdyHeaderBar

[Adrien Plazas <aplazas src gnome org>]

commit f187c5b1299eab71e2919fd7503085e558d86d73
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Tue Sep 10 19:17:51 2019 +0200

    header-bar: Make it a HdyHeaderBar
    
    This is needed to make the view switcher work well.

 data/ui/header-bar.ui | 3 ++-
 src/header-bar.vala   | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/data/ui/header-bar.ui b/data/ui/header-bar.ui
index effa992..20ef1bd 100644
--- a/data/ui/header-bar.ui
+++ b/data/ui/header-bar.ui
@@ -2,9 +2,10 @@
 <interface>
   <!-- interface-requires gtk+ 3.12 -->
 
-  <template class="UsageHeaderBar" parent="GtkHeaderBar">
+  <template class="UsageHeaderBar" parent="HdyHeaderBar">
     <property name="visible">True</property>
     <property name="show-close-button">True</property>
+    <property name="centering-policy">strict</property>
     <child type="title">
       <object class="GtkStackSwitcher" id="stack_switcher">
         <property name="visible">True</property>
diff --git a/src/header-bar.vala b/src/header-bar.vala
index 8d470dc..3ff613d 100644
--- a/src/header-bar.vala
+++ b/src/header-bar.vala
@@ -29,7 +29,7 @@ namespace Usage
     }
 
     [GtkTemplate (ui = "/org/gnome/Usage/ui/header-bar.ui")]
-    public class HeaderBar : Gtk.HeaderBar
+    public class HeaderBar : Hdy.HeaderBar
     {
         [GtkChild]
         private Gtk.StackSwitcher stack_switcher;