Aura on Linux: Make a DesktopScreenX11 to match the windows one.

ui/aura/root_window_host_linux.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_AURA_ROOT_WINDOW_HOST_LINUX_H_
 #define UI_AURA_ROOT_WINDOW_HOST_LINUX_H_
 #pragma once
 
 #include <X11/Xlib.h>
 
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "ui/aura/root_window_host.h"
 #include "ui/gfx/rect.h"
 
+namespace ui {
+class ViewProp;
+}
+
 namespace aura {
 
 class RootWindowHostLinux : public RootWindowHost,
                             public MessageLoop::Dispatcher {
  public:
   explicit RootWindowHostLinux(const gfx::Rect& bounds);
   virtual ~RootWindowHostLinux();
 
   // Overridden from Dispatcher overrides:
   virtual bool Dispatch(const base::NativeEvent& event) OVERRIDE;
@@ skipping 59 matching lines @@
 
     ATOM_COUNT
   };
   ::Atom cached_atoms_[ATOM_COUNT];
 
   // True if the window should be focused when the window is shown.
   bool focus_when_shown_;
 
   scoped_array<XID> pointer_barriers_;
 
+  scoped_ptr<ui::ViewProp> prop_;
+
   DISALLOW_COPY_AND_ASSIGN(RootWindowHostLinux);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_HOST_LINUX_H_