cros: Adds ShellPort functions for simplified display mode

ash/host/ash_window_tree_host.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.h"
 
 #include "ash/host/ash_window_tree_host_init_params.h"
 #include "ash/host/ash_window_tree_host_unified.h"
+#include "ash/shell_port.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/event.h"
 #include "ui/gfx/geometry/rect.h"
 
 #if defined(USE_OZONE)
 #include "ash/host/ash_window_tree_host_platform.h"
 #elif defined(USE_X11)
 #include "ash/host/ash_window_tree_host_x11.h"
 #endif
@@ skipping 23 matching lines @@
     screen_position_client->ConvertPointFromScreen(root_window, &location);
     wth->ConvertDIPToPixels(&location);
     event->set_location(location);
     event->set_root_location(location);
   }
 }
 
 // static
 AshWindowTreeHost* AshWindowTreeHost::Create(
     const AshWindowTreeHostInitParams& init_params) {
+  AshWindowTreeHost* ash_window_tree_host =
+      ShellPort::Get()->CreateAshWindowTreeHost(init_params);
+  if (ash_window_tree_host)
+    return ash_window_tree_host;
+
   if (init_params.offscreen)
     return new AshWindowTreeHostUnified(init_params.initial_bounds);
 #if defined(USE_OZONE)
   return new AshWindowTreeHostPlatform(init_params.initial_bounds);
 #elif defined(USE_X11)
   return new AshWindowTreeHostX11(init_params.initial_bounds);
 #else
 #error Unsupported platform.
 #endif
 }
 
 }  // namespace ash