Adds ability for WindowManager to create display roots

ui/aura/mus/window_tree_client.h

 // 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.
 
 #ifndef UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 #define UI_AURA_MUS_WINDOW_TREE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 95 matching lines @@
       WindowManagerDelegate* window_manager_delegate = nullptr,
       ui::mojom::WindowTreeClientRequest request = nullptr,
       scoped_refptr<base::SingleThreadTaskRunner> io_task_runner = nullptr,
       bool create_discardable_memory = true);
   ~WindowTreeClient() override;
 
   // Establishes the connection by way of the WindowTreeFactory.
   void ConnectViaWindowTreeFactory();
 
   // Establishes the connection by way of WindowManagerWindowTreeFactory.
-  void ConnectAsWindowManager();
+  // See mojom for details on |automatically_create_display_roots|.
+  void ConnectAsWindowManager(bool automatically_create_display_roots = true);
 
   service_manager::Connector* connector() { return connector_; }
   ui::Gpu* gpu() { return gpu_.get(); }
   CaptureSynchronizer* capture_synchronizer() {
     return capture_synchronizer_.get();
   }
   FocusSynchronizer* focus_synchronizer() { return focus_synchronizer_.get(); }
 
   bool connected() const { return tree_ != nullptr; }
   ClientSpecificId client_id() const { return client_id_; }
@@ skipping 482 matching lines @@
   bool got_initial_displays_ = false;
 
   base::WeakPtrFactory<WindowTreeClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClient);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_TREE_CLIENT_H_