[gnome-shell/wip/exalm/wallpaper] background: Check xml mime type instead of extension

[Marge Bot <marge-bot src gnome org>]

commit 58ed969dd1f71e05d68455cd00369956160b5216
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Fri Apr 16 19:17:33 2021 +0500

    background: Check xml mime type instead of extension
    
    This is required to be able to set animated wallpapers with the wallpaper
    portal, which names them 'background' without an extension.
    
    See https://gitlab.gnome.org/bertob/nostalgia/-/merge_requests/12
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1816>

 js/ui/background.js | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/background.js b/js/ui/background.js
index df2d98112f..1f7c5e5720 100644
--- a/js/ui/background.js
+++ b/js/ui/background.js
@@ -101,6 +101,8 @@ const LoginManager = imports.misc.loginManager;
 const Main = imports.ui.main;
 const Params = imports.misc.params;
 
+Gio._promisify(Gio._LocalFilePrototype, 'query_info_async', 'query_info_finish');
+
 var DEFAULT_BACKGROUND_COLOR = Clutter.Color.from_pixel(0x2e3436ff);
 
 const BACKGROUND_SCHEMA = 'org.gnome.desktop.background';
@@ -479,8 +481,15 @@ var Background = GObject.registerClass({
         }
     }
 
-    _loadFile(file) {
-        if (file.get_basename().endsWith('.xml'))
+    async _loadFile(file) {
+        const info = await file.query_info_async(
+            Gio.FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE,
+            Gio.FileQueryInfoFlags.NONE,
+            0,
+            null);
+
+        const contentType = info.get_content_type();
+        if (contentType === 'application/xml')
             this._loadAnimation(file);
         else
             this._loadImage(file);