ui: move userAvatar to own file

There are a few places in the code that use the UserAvatar widget
without using the user menu.

Since the avatar is used outside of the user menu, move it from
userMenu.js to its own file.

js/ui/userAvatar.js

@@ -0,0 +1,52 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const Gio = imports.gi.Gio;
+const GLib = imports.gi.GLib;
+const Lang = imports.lang;
+const St = imports.gi.St;
+
+const Params = imports.misc.params;
+
+const DIALOG_ICON_SIZE = 64;
+
+// Adapted from gdm/gui/user-switch-applet/applet.c
+//
+// Copyright (C) 2004-2005 James M. Cape <jcape@ignore-your.tv>.
+// Copyright (C) 2008,2009 Red Hat, Inc.
+
+const UserAvatar = new Lang.Class({
+    Name: 'UserAvatar',
+
+    _init: function(user, params) {
+        this._user = user;
+        params = Params.parse(params, { reactive: false,
+                                        iconSize: DIALOG_ICON_SIZE,
+                                        styleClass: 'status-chooser-user-icon' });
+        this._iconSize = params.iconSize;
+
+        this.actor = new St.Bin({ style_class: params.styleClass,
+                                  track_hover: params.reactive,
+                                  reactive: params.reactive });
+    },
+
+    setSensitive: function(sensitive) {
+        this.actor.can_focus = sensitive;
+        this.actor.reactive = sensitive;
+    },
+
+    update: function() {
+        let iconFile = this._user.get_icon_file();
+        if (iconFile && !GLib.file_test(iconFile, GLib.FileTest.EXISTS))
+            iconFile = null;
+
+        if (iconFile) {
+            let file = Gio.File.new_for_path(iconFile);
+            this.actor.child = null;
+            this.actor.style = 'background-image: url("%s");'.format(iconFile);
+        } else {
+            this.actor.style = null;
+            this.actor.child = new St.Icon({ icon_name: 'avatar-default-symbolic',
+                                             icon_size: this._iconSize });
+        }
+    }
+});