On Linux, the App Launcher is now shown in the taskbar.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index fc15fc58d2adbfec79f2f7f710b07fcdfe053019..8c5850bfdd8b72723ddf162363fb7eaa57dba82b 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -325,6 +325,9 @@ void AppListView::OnBeforeBubbleWidgetInit(
   // Set up a custom WM_CLASS for the app launcher window. This allows task
   // switchers in X11 environments to distinguish it from main browser windows.
   params->wm_class_name = kAppListWMClass;
+  // Show the window in the taskbar, even though it is a bubble, which would not
+  // normally be shown.
+  params->force_show_in_taskbar = true;
 #endif
 }