[gnome-usage] theme: Drop Adwaita-dark custom CSS

[Gitlab Administrative User <gitlab src gnome org>]

commit 6ee77e8498e7bcb5557a3bc52693e61996555ce4
Author: Felipe Borges <felipeborges gnome org>
Date:   Wed Oct 25 14:48:48 2017 +0200

    theme: Drop Adwaita-dark custom CSS
    
    The CSS definitions in the stylesheeet should be theme-independent
    enough.

 data/interface/adwaita-dark.css    | 140 -------------------------------------
 data/org.gnome.Usage.gresource.xml |   1 -
 src/window.vala                    |   8 +--
 3 files changed, 1 insertion(+), 148 deletions(-)
---
diff --git a/data/org.gnome.Usage.gresource.xml b/data/org.gnome.Usage.gresource.xml
index a8ce162..cafe52c 100644
--- a/data/org.gnome.Usage.gresource.xml
+++ b/data/org.gnome.Usage.gresource.xml
@@ -2,7 +2,6 @@
 <gresources>
     <gresource prefix="/org/gnome/Usage">
         <file compressed="true">interface/adwaita.css</file>
-        <file compressed="true">interface/adwaita-dark.css</file>
         <file preprocess="xml-stripblanks">ui/header-bar.ui</file>
         <file preprocess="xml-stripblanks">ui/performance-view.ui</file>
         <file preprocess="xml-stripblanks">ui/process-dialog.ui</file>
diff --git a/src/window.vala b/src/window.vala
index 2cce793..a4109fc 100644
--- a/src/window.vala
+++ b/src/window.vala
@@ -86,15 +86,9 @@ namespace Usage
 
         private void load_css()
         {
-            string name_css = "adwaita.css";
-            var settings = Gtk.Settings.get_for_screen(get_screen());
-
-            if(settings.gtk_application_prefer_dark_theme)
-                name_css = "adwaita-dark.css";
-
             var provider = new Gtk.CssProvider();
             Gtk.StyleContext.reset_widgets(get_screen());
-            provider.load_from_resource("/org/gnome/Usage/interface/" + name_css);
+            provider.load_from_resource("/org/gnome/Usage/interface/adwaita.css");
             Gtk.StyleContext.add_provider_for_screen(get_screen(), provider, 
Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION);
         }
     }