Make the member |is_cursor_visible_| in DesktopWindowTreeHostWin static.

ui/views/widget/desktop_aura/desktop_root_window_host_win.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 UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_ROOT_WINDOW_HOST_WIN_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_ROOT_WINDOW_HOST_WIN_H_
 
 #include "ui/aura/client/animation_host.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/views/views_export.h"
@@ skipping 255 matching lines @@
 
   // True if the widget is going to have a non_client_view. We cache this value
   // rather than asking the Widget for the non_client_view so that we know at
   // Init time, before the Widget has created the NonClientView.
   bool has_non_client_view_;
 
   // Owned by TooltipController, but we need to forward events to it so we keep
   // a reference.
   corewm::TooltipWin* tooltip_;
 
-  // State of the cursor.
-  bool is_cursor_visible_;
+  // Visibility of the cursor. On Windows we can have multiple root windows and
+  // the implementation of ::ShowCursor() is based on a counter, so making this
+  // member static ensures that ::ShowCursor() is always called exactly once
+  // whenever the cursor visibility state changes.
+  static bool is_cursor_visible_;
 
   scoped_ptr<aura::client::ScopedTooltipDisabler> tooltip_disabler_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostWin);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_ROOT_WINDOW_HOST_WIN_H_