Adds ability for WindowManager to create display roots

services/ui/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 "services/ui/ws/display_binding.h"
 
 #include "base/memory/ptr_util.h"
 #include "services/service_manager/public/interfaces/connector.mojom.h"
 #include "services/ui/ws/display.h"
 #include "services/ui/ws/window_manager_access_policy.h"
@@ skipping 13 matching lines @@
       binding_(display, std::move(request)),
       client_(std::move(client)) {}
 
 DisplayBindingImpl::~DisplayBindingImpl() {}
 
 WindowTree* DisplayBindingImpl::CreateWindowTree(ServerWindow* root) {
   const uint32_t embed_flags = 0;
   WindowTree* tree = window_server_->EmbedAtWindow(
       root, user_id_, std::move(client_), embed_flags,
       base::WrapUnique(new WindowManagerAccessPolicy));
-  tree->ConfigureWindowManager();
+  const bool automatically_create_display_roots = true;
+  tree->ConfigureWindowManager(automatically_create_display_roots);
   return tree;
 }
 
 }  // namespace ws
 }  // namespace ui