exo: Fix multi-display hardware cursor

ash/wm/ash_native_cursor_manager.h

 // Copyright (c) 2012 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_WM_ASH_NATIVE_CURSOR_MANAGER_H_
 #define ASH_WM_ASH_NATIVE_CURSOR_MANAGER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/wm/core/native_cursor_manager.h"
 #include "ui/wm/core/native_cursor_manager_delegate.h"
 
 namespace ui {
 class ImageCursors;
 }
 
 namespace ash {
 
 namespace test {
 class CursorManagerTestApi;
 }
 
 // This does the ash-specific setting of cursor details like cursor
 // visibility. It communicates back with the CursorManager through the
 // NativeCursorManagerDelegate interface, which receives messages about what
 // changes were acted on.
 class ASH_EXPORT AshNativeCursorManager : public ::wm::NativeCursorManager {
  public:
+  class Observer {
+   public:
+    virtual void OnCursorDisplayChanging(const display::Display& display) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
   AshNativeCursorManager();
   ~AshNativeCursorManager() override;
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
   // Toggle native cursor enabled/disabled.
   // The native cursor is enabled by default. When disabled, we hide the native
   // cursor regardless of visibility state, and let CursorWindowManager draw
   // the cursor.
   void SetNativeCursorEnabled(bool enabled);
 
  private:
   friend class test::CursorManagerTestApi;
 
   // Overridden from ::wm::NativeCursorManager:
   void SetDisplay(const display::Display& display,
                   ::wm::NativeCursorManagerDelegate* delegate) override;
   void SetCursor(gfx::NativeCursor cursor,
                  ::wm::NativeCursorManagerDelegate* delegate) override;
   void SetVisibility(bool visible,
                      ::wm::NativeCursorManagerDelegate* delegate) override;
   void SetCursorSet(ui::CursorSetType cursor_set,
                     ::wm::NativeCursorManagerDelegate* delegate) override;
   void SetMouseEventsEnabled(
       bool enabled,
       ::wm::NativeCursorManagerDelegate* delegate) override;
 
   // The cursor location where the cursor was disabled.
   gfx::Point disabled_cursor_location_;
 
   bool native_cursor_enabled_;
 
   std::unique_ptr<ui::ImageCursors> image_cursors_;
 
+  base::ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(AshNativeCursorManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_ASH_NATIVE_CURSOR_MANAGER_H_