[Aura] Support always-on-top top level window.

ui/aura_shell/test/aura_shell_test_base.h

+// Copyright (c) 2011 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_AURA_SHELL_TEST_AURA_SHELL_TEST_BASE_H_
+#define UI_AURA_SHELL_TEST_AURA_SHELL_TEST_BASE_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "ui/aura/test/aura_test_base.h"
+
+namespace aura_shell {
+namespace test {
+
+class AuraShellTestBase : public aura::test::AuraTestBase {
+ public:
+  AuraShellTestBase();
+  virtual ~AuraShellTestBase();
+
+  // testing::Test:
+  virtual void SetUp() OVERRIDE;
+  virtual void TearDown() OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AuraShellTestBase);
+};
+
+}  // namespace test
+}  // namespace aura_shell
+
+#endif  // UI_AURA_SHELL_TEST_AURA_SHELL_TEST_BASE_H_