In Chromium, App Launcher's WM_CLASS is "chromium_app_list".

chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc

Index: chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc
diff --git a/chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc b/chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc
index 040d8b7f9daf2519ddf2e7917ae2c2346bf856a4..c018eabf77b18386be7e16688449ac20e2c37073 100644
--- a/chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc
+++ b/chrome/browser/ui/views/app_list/linux/app_list_service_linux.cc
@@ -38,8 +38,6 @@ class AppListFactoryLinux : public AppListFactory {
                                       cursor,
                                       views::BubbleBorder::FLOAT,
                                       false /* border_accepts_events */);
-    // TODO(mgiuca): Set the app launcher window's WM_CLASS so that it can be
-    // associated with its own launch icon in the window manager.
     return new AppListLinux(view, on_should_dismiss);
   }