mus: Changes SetDisplayRoot() to create actual display

services/ui/display/screen_manager_forwarding.h

 // Copyright 2017 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_DISPLAY_SCREEN_MANAGER_FORWARDING_H_
 #define SERVICES_UI_DISPLAY_SCREEN_MANAGER_FORWARDING_H_
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
@@ skipping 18 matching lines @@
       public mojom::NativeDisplayDelegate,
       service_manager::InterfaceFactory<mojom::NativeDisplayDelegate> {
  public:
   ScreenManagerForwarding();
   ~ScreenManagerForwarding() override;
 
   // ScreenManager:
   void AddInterfaces(service_manager::BinderRegistry* registry) override;
   void Init(ScreenManagerDelegate* delegate) override;
   void RequestCloseDisplay(int64_t display_id) override;
+  display::ScreenBase* GetScreen() override;
 
   // NativeDisplayObserver:
   void OnConfigurationChanged() override;
   void OnDisplaySnapshotsInvalidated() override;
 
   // mojom::NativeDisplayDelegate:
   void Initialize(mojom::NativeDisplayObserverPtr observer) override;
   void TakeDisplayControl(const TakeDisplayControlCallback& callback) override;
   void RelinquishDisplayControl(
       const RelinquishDisplayControlCallback& callback) override;
@@ skipping 24 matching lines @@
       const std::vector<DisplaySnapshot*>& displays);
 
   // Forwards results from call to Configure() back with |callback|.
   void ForwardConfigure(
       DisplaySnapshot* snapshot,
       const DisplayMode* mode,
       const gfx::Point& origin,
       const mojom::NativeDisplayDelegate::ConfigureCallback& callback,
       bool status);
 
+  std::unique_ptr<display::ScreenBase> screen_;
   mojo::Binding<mojom::NativeDisplayDelegate> binding_;
   mojom::NativeDisplayObserverPtr observer_;
 
   std::unique_ptr<display::NativeDisplayDelegate> native_display_delegate_;
 
   // Cached pointers to snapshots owned by the |native_display_delegate_|.
   std::unordered_map<int64_t, DisplaySnapshot*> snapshot_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenManagerForwarding);
 };
 
 }  // namespace display
 
 #endif  // SERVICES_UI_DISPLAY_SCREEN_MANAGER_FORWARDING_H_