Fix software mirror mode on Ozone part 2/2

ash/host/ash_window_tree_host_x11.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 ASH_HOST_ASH_WINDOW_TREE_HOST_X11_H_
 #define ASH_HOST_ASH_WINDOW_TREE_HOST_X11_H_
 
 #include "ash/ash_export.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/host/transformer_helper.h"
@@ skipping 14 matching lines @@
 
  private:
   // AshWindowTreeHost:
   void ToggleFullScreen() override;
   bool ConfineCursorToRootWindow() override;
   void UnConfineCursor() override;
   void SetRootWindowTransformer(
       scoped_ptr<RootWindowTransformer> transformer) override;
   gfx::Insets GetHostInsets() const override;
   aura::WindowTreeHost* AsWindowTreeHost() override;
-  void UpdateDisplayID(int64 id1, int64 id2) override;
   void PrepareForShutdown() override;
 
   // aura::WindowTreehost:
   void SetBounds(const gfx::Rect& bounds) override;
   gfx::Transform GetRootTransform() const override;
   void SetRootTransform(const gfx::Transform& transform) override;
   gfx::Transform GetInverseRootTransform() const override;
   void UpdateRootWindowSize(const gfx::Size& host_size) override;
   void OnCursorVisibilityChangedNative(bool show) override;
 
   // aura::WindowTreeHostX11:
   void OnConfigureNotify() override;
   bool CanDispatchEvent(const ui::PlatformEvent& event) override;
   void TranslateAndDispatchLocatedEvent(ui::LocatedEvent* event) override;
 
   // EnvObserver overrides.
   void OnWindowInitialized(aura::Window* window) override;
   void OnHostInitialized(aura::WindowTreeHost* host) override;
 
 #if defined(OS_CHROMEOS)
   // Set the CrOS touchpad "tap paused" property. It is used to temporarily
   // turn off the Tap-to-click feature when the mouse pointer is invisible.
   void SetCrOSTapPaused(bool state);
 #endif
 
   scoped_ptr<XID[]> pointer_barriers_;
 
   TransformerHelper transformer_helper_;
 
-  // The display IDs associated with this root window.
-  // In single monitor or extended mode dual monitor case, the root window
-  // is associated with one display.
-  // In mirror mode dual monitors case, the root window is associated with
-  // both displays.
-  std::pair<int64, int64> display_ids_;
-
   DISALLOW_COPY_AND_ASSIGN(AshWindowTreeHostX11);
 };
 
 }  // namespace ash
 
 #endif  // ASH_HOST_ASH_WINDOW_TREE_HOST_X11_H_