Adds ability for WindowManager to create display roots

services/ui/ws/display_manager.h

 // 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.
 
 #ifndef SERVICES_UI_WS_DISPLAY_MANAGER_H_
 #define SERVICES_UI_WS_DISPLAY_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 11 matching lines @@
 
 class CursorLocationManager;
 class Display;
 class ServerWindow;
 class UserDisplayManager;
 class UserIdTracker;
 class WindowManagerDisplayRoot;
 class WindowServer;
 
 // DisplayManager manages the set of Displays. DisplayManager distinguishes
-// between displays that do yet have an accelerated widget (pending), vs
+// between displays that do not yet have an accelerated widget (pending), vs
 // those that do.
 class DisplayManager : public UserIdTrackerObserver,
                        public display::ScreenManagerDelegate {
  public:
   DisplayManager(WindowServer* window_server, UserIdTracker* user_id_tracker);
   ~DisplayManager() override;
 
   // Returns the UserDisplayManager for |user_id|. DisplayManager owns the
   // return value.
   UserDisplayManager* GetUserDisplayManager(const UserId& user_id);
@@ skipping 74 matching lines @@
   // ID to use for next root node.
   ClientSpecificId next_root_id_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayManager);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DISPLAY_MANAGER_H_