Add PlatformScreenDelegate and start implementation.

services/ui/ws/window_tree_host_factory.cc

 // Copyright 2016 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 "services/ui/ws/window_tree_host_factory.h"
 
 #include "services/ui/surfaces/surfaces_state.h"
 #include "services/ui/ws/display.h"
 #include "services/ui/ws/display_binding.h"
 #include "services/ui/ws/window_server.h"
 
 namespace ui {
 namespace ws {
 
-WindowTreeHostFactory::WindowTreeHostFactory(
-    WindowServer* window_server,
-    const UserId& user_id,
-    const PlatformDisplayInitParams& platform_display_init_params)
-    : window_server_(window_server),
-      user_id_(user_id),
-      platform_display_init_params_(platform_display_init_params) {}
+WindowTreeHostFactory::WindowTreeHostFactory(WindowServer* window_server,
+                                             const UserId& user_id)
+    : window_server_(window_server), user_id_(user_id) {
+  platform_display_init_params_.surfaces_state =
+      window_server_->GetSurfacesState();
+}
 
 WindowTreeHostFactory::~WindowTreeHostFactory() {}
 
 void WindowTreeHostFactory::AddBinding(
     mojom::WindowTreeHostFactoryRequest request) {
   bindings_.AddBinding(this, std::move(request));
 }
 
 void WindowTreeHostFactory::CreateWindowTreeHost(
     mojom::WindowTreeHostRequest host,
     mojom::WindowTreeClientPtr tree_client) {
   Display* display = new Display(window_server_, platform_display_init_params_);
   std::unique_ptr<DisplayBindingImpl> display_binding(
       new DisplayBindingImpl(std::move(host), display, user_id_,
                              std::move(tree_client), window_server_));
   display->Init(std::move(display_binding));
 }
 
 }  // namespace ws
 }  // namespace ui