Makes WindowTree take the AccessPolicy

components/mus/ws/display_binding.cc

 // Copyright 2015 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 "components/mus/ws/display_binding.h"
 
 #include "components/mus/ws/connection_manager.h"
 #include "components/mus/ws/display.h"
+#include "components/mus/ws/window_manager_access_policy.h"
 #include "components/mus/ws/window_tree.h"
 #include "mojo/shell/public/interfaces/connector.mojom.h"
 
 namespace mus {
 namespace ws {
 
 DisplayBindingImpl::DisplayBindingImpl(mojom::WindowTreeHostRequest request,
                                        Display* display,
                                        const UserId& user_id,
                                        mojom::WindowTreeClientPtr client,
                                        ConnectionManager* manager)
     : connection_manager_(manager),
       user_id_(user_id),
       binding_(display, std::move(request)),
       client_(std::move(client)) {}
 
 DisplayBindingImpl::~DisplayBindingImpl() {}
 
 WindowTree* DisplayBindingImpl::CreateWindowTree(ServerWindow* root) {
-  WindowTree* tree =
-      connection_manager_->EmbedAtWindow(root, user_id_, std::move(client_));
+  WindowTree* tree = connection_manager_->EmbedAtWindow(
+      root, user_id_, std::move(client_),
+      make_scoped_ptr(new WindowManagerAccessPolicy));
   tree->ConfigureWindowManager();
   return tree;
 }
 
 }  // namespace ws
 }  // namespace mus