base: Remove a file that is no longer used.

base/no_windows2000_unittest.h

-// Copyright (c) 2006-2008 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 BASE_NO_WINDOWS2000_UNITTEST_H_
-#define BASE_NO_WINDOWS2000_UNITTEST_H_
-#pragma once
-
-#include "testing/gtest/include/gtest/gtest.h"
-#include "base/win_util.h"
-
-// Disable the whole test case when executing on Windows 2000 or lower.
-// Note: Parent should be testing::Test or UITest.
-template<typename Parent>
-class NoWindows2000Test : public Parent {
- public:
-  static bool IsTestCaseDisabled() {
-    return win_util::GetWinVersion() <= win_util::WINVERSION_2000;
-  }
-};
-
-#endif  // BASE_NO_WINDOWS2000_UNITTEST_H_