window-list: Update icon on app changes

We currently assume that the application associated with a particular
window is fixed. While this holds true for almost every application,
there are some cases of multi-app-packages like LibreOffice where
windows may change the properties used for application matching at
runtime. Catch those cases to make sure we display the correct icon
when the window shifts applications.

https://bugzilla.gnome.org/show_bug.cgi?id=771731

extensions/window-list/extension.js

@@ -152,6 +152,12 @@ const WindowTitle = new Lang.Class({
         this._iconThemeChangedId =
             this._textureCache.connect('icon-theme-changed',
                                        Lang.bind(this, this._updateIcon));
+        this._notifyWmClass =
+            this._metaWindow.connect('notify::wm-class',
+                                     Lang.bind(this, this._updateIcon));
+        this._notifyAppId =
+            this._metaWindow.connect('notify::gtk-application-id',
+                                     Lang.bind(this, this._updateIcon));
         this._updateIcon();
 
         this.actor.connect('destroy', Lang.bind(this, this._onDestroy));
@@ -193,6 +199,8 @@ const WindowTitle = new Lang.Class({
         this._textureCache.disconnect(this._iconThemeChangedId);
         this._metaWindow.disconnect(this._notifyTitleId);
         this._metaWindow.disconnect(this._notifyMinimizedId);
+        this._metaWindow.disconnect(this._notifyWmClass);
+        this._metaWindow.disconnect(this._notifyAppId);
     }
 });