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

ui/views/widget/widget.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_WIDGET_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 
 #include <set>
 #include <stack>
 #include <vector>
@@ skipping 207 matching lines @@
     // aura::Window. Default is LAYER_TEXTURED.
     ui::LayerType layer_type;
     // Only used by Aura. Provides a context window whose RootWindow is
     // consulted during widget creation to determine where in the Window
     // hierarchy this widget should be placed. (This is separate from |parent|;
     // if you pass a RootWindow to |parent|, your window will be parented to
     // |parent|. If you pass a RootWindow to |context|, we ask that RootWindow
     // where it wants your window placed.) NULL is not allowed if you are using
     // aura.
     gfx::NativeView context;
+    // If true, forces the window to be shown in the taskbar, even for window
+    // types that do not appear in the taskbar by default (popup and bubble).
+    // Currently only used by X11.
+    // TODO(mgiuca): Respect this flag in Windows (http://crbug.com/332277).
+    bool force_show_in_taskbar;
     // Only used by X11, for root level windows. Specifies the res_name and
     // res_class fields, respectively, of the WM_CLASS window property. Controls
     // window grouping and desktop file matching in Linux window managers.
     std::string wm_role_name;
     std::string wm_class_name;
     std::string wm_class_class;
   };
 
   Widget();
   virtual ~Widget();
@@ skipping 649 matching lines @@
   // True when window movement via mouse interaction with the frame should be
   // disabled.
   bool movement_disabled_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_