extensionPrefs: Export parent window for prefs dialog

Now that OpenExtensionPrefs()'s parentWindow parameter is actually
supported, export the main application window so it can act as
transient parent to the prefs dialog.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1087

js/extensionPrefs/js/main.js

@@ -4,7 +4,7 @@ imports.gi.versions.Gtk = '3.0';
 
 const Gettext = imports.gettext;
 const Package = imports.package;
-const { Gdk, GLib, Gio, GObject, Gtk } = imports.gi;
+const { Gdk, GLib, Gio, GObject, Gtk, Shew } = imports.gi;
 
 Package.initFormat();
 
@@ -15,6 +15,8 @@ const { ExtensionState, ExtensionType } = ExtensionUtils;
 const GnomeShellIface = loadInterfaceXML('org.gnome.Shell.Extensions');
 const GnomeShellProxy = Gio.DBusProxy.makeProxyWrapper(GnomeShellIface);
 
+Gio._promisify(Shew.WindowExporter.prototype, 'export', 'export_finish');
+
 function loadInterfaceXML(iface) {
     const uri = 'resource:///org/gnome/Extensions/dbus-interfaces/%s.xml'.format(iface);
     const f = Gio.File.new_for_uri(uri);
@@ -89,6 +91,9 @@ var ExtensionsWindow = GObject.registerClass({
 
         this._updatesCheckId = 0;
 
+        this._exporter = new Shew.WindowExporter({ window: this });
+        this._exportedHandle = '';
+
         this._mainBox.set_focus_vadjustment(this._scrolledWindow.vadjustment);
 
         let action;
@@ -152,9 +157,17 @@ var ExtensionsWindow = GObject.registerClass({
         dialog.present();
     }
 
-    openPrefs(uuid) {
+    async openPrefs(uuid) {
+        if (!this._exportedHandle) {
+            try {
+                this._exportedHandle = await this._exporter.export();
+            } catch (e) {
+                log('Failed to export window: %s'.format(e.message));
+            }
+        }
+
         this._shellProxy.OpenExtensionPrefsRemote(uuid,
-            '',
+            this._exportedHandle,
             { modal: new GLib.Variant('b', true) });
     }