views: Extract SystemMenuModel from native_menu_win.*.

chrome/browser/ui/views/frame/system_menu_model.cc

+// 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.
+
+#include "chrome/browser/ui/views/frame/system_menu_model.h"
+
+#include <windows.h>
+
+#include <algorithm>
+
+SystemMenuModel::SystemMenuModel(ui::SimpleMenuModel::Delegate* delegate)
+    : ui::SimpleMenuModel(delegate) {
+}
+
+SystemMenuModel::~SystemMenuModel() {
+}
+
+int SystemMenuModel::GetFirstItemIndex(gfx::NativeMenu native_menu) const {
+  // We allow insertions before last item (Close).
+  return std::max(0, GetMenuItemCount(native_menu) - 1);
+}
+
+int SystemMenuModel::FlipIndex(int index) const {
+  return GetItemCount() - index - 1;
+}