Add ScopedMacRTL class for Cocoa browser RTL testing

ui/base/test/scoped_mac_rtl.h

+// Copyright 2016 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_BASE_TEST_SCOPED_MAC_RTL_H_
+#define UI_BASE_TEST_SCOPED_MAC_RTL_H_
+
+#include <string>
+
+#include "base/test/scoped_feature_list.h"
+
+namespace ui {
+
+// Enables all flags required for
+// |ui::ShouldDoExperimentalRTLLayout| to return true.
+class ScopedEnableMacRTLLayout final {
+ public:
+  ScopedEnableMacRTLLayout();
+  ~ScopedEnableMacRTLLayout();
+
+ private:
+  BOOL original_apple_text_direction_;
+  BOOL original_rtl_writing_direction_;
+  std::string original_locale_;
+  base::test::ScopedFeatureList scoped_feature_list_;
+  DISALLOW_COPY_AND_ASSIGN(ScopedEnableMacRTLLayout);
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_TEST_SCOPED_MAC_RTL_H_