Unify display ids between Display and PlatformDisplay.

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 50 matching lines @@
 
   bool has_displays() const { return !displays_.empty(); }
   bool has_active_or_pending_displays() const {
     return !displays_.empty() || !pending_displays_.empty();
   }
 
   // Returns the id for the next root window (both for the root of a Display
   // as well as the root of WindowManagers).
   WindowId GetAndAdvanceNextRootId();
 
-  uint32_t GetAndAdvanceNextDisplayId();
-
   // Called when the AcceleratedWidget is available for |display|.
   void OnDisplayAcceleratedWidgetAvailable(Display* display);
 
  private:
   // UserIdTrackerObserver:
   void OnActiveUserIdChanged(const UserId& previously_active_id,
                              const UserId& active_id) override;
 
   DisplayManagerDelegate* delegate_;
   UserIdTracker* user_id_tracker_;
 
   // Displays are initially added to |pending_displays_|. When the display is
   // initialized it is moved to |displays_|. WindowServer owns the Displays.
   std::set<Display*> pending_displays_;
   std::set<Display*> displays_;
 
   std::map<UserId, std::unique_ptr<UserDisplayManager>> user_display_managers_;
 
   // ID to use for next root node.
   ClientSpecificId next_root_id_;
 
-  uint32_t next_display_id_;
-
   DISALLOW_COPY_AND_ASSIGN(DisplayManager);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DISPLAY_MANAGER_H_