Unified Desktop: hook up ash to allow unified desktop mode

ash/host/ash_window_tree_host_x11.cc

 // Copyright 2014 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.
 
 #include "ash/host/ash_window_tree_host_x11.h"
 
 #include <X11/extensions/Xfixes.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 
 #include <string>
 #include <vector>
 
 #include "ash/host/ash_window_tree_host_init_params.h"
+#include "ash/host/ash_window_tree_host_virtual.h"
 #include "ash/host/root_window_transformer.h"
 #include "base/basictypes.h"
 #include "base/sys_info.h"
 #include "ui/aura/env.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/events/devices/device_data_manager.h"
 #include "ui/events/devices/x11/device_list_cache_x11.h"
 #include "ui/events/devices/x11/touch_factory_x11.h"
@@ skipping 247 matching lines @@
                        PropModeReplace,
                        &value,
                        1);
     }
   }
 }
 #endif
 
 AshWindowTreeHost* AshWindowTreeHost::Create(
     const AshWindowTreeHostInitParams& init_params) {
+  if (init_params.offscreen)
+    return new AshWindowTreeHostVirtual(init_params.initial_bounds);
   return new AshWindowTreeHostX11(init_params.initial_bounds);
 }
 
 }  // namespace ash