X11: Handle change notify for _NET_WORKAREA

ui/views/widget/desktop_aura/desktop_screen_x11.h

Index: ui/views/widget/desktop_aura/desktop_screen_x11.h
diff --git a/ui/views/widget/desktop_aura/desktop_screen_x11.h b/ui/views/widget/desktop_aura/desktop_screen_x11.h
index 31f5f02a3ae280ce41100d994820b8d1a5069e5e..fb755d92402795651425133839acbc12e588177d 100644
--- a/ui/views/widget/desktop_aura/desktop_screen_x11.h
+++ b/ui/views/widget/desktop_aura/desktop_screen_x11.h
@@ -14,6 +14,7 @@
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/display_change_notifier.h"
 #include "ui/gfx/screen.h"
+#include "ui/gfx/x/x11_atom_cache.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
@@ -94,6 +95,8 @@ class VIEWS_EXPORT DesktopScreenX11 : public gfx::Screen,
 
   gfx::DisplayChangeNotifier change_notifier_;
 
+  ui::X11AtomCache atom_cache_;
+
   DISALLOW_COPY_AND_ASSIGN(DesktopScreenX11);
 };