Add ScopedMacRTL class for Cocoa browser RTL testing

chrome/browser/ui/cocoa/test/scoped_force_rtl_mac.mm

+// 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.
+
+#include "chrome/browser/ui/cocoa/test/scoped_force_rtl_mac.h"
+
+#import <Foundation/Foundation.h>
+
+#include "base/i18n/rtl.h"
+#include "chrome/browser/ui/cocoa/l10n_util.h"
+
+namespace {
+
+NSString* const kAppleTextDirectionDefaultsKey = @"AppleTextDirection";
+NSString* const kForceRTLWritingDirectionDefaultsKey =
+    @"NSForceRightToLeftWritingDirection";
+const char kDefaultRTLLocale[] = "he";  // Hebrew.
+
+}  // namespace
+
+namespace cocoa_l10n_util {
+
+ScopedForceRTLMac::ScopedForceRTLMac() {
+  scoped_feature_list_.InitAndEnableFeature(kExperimentalMacRTL);
+  NSUserDefaults* standard_defaults = [NSUserDefaults standardUserDefaults];
+  original_apple_text_direction_ =
+      [standard_defaults boolForKey:kAppleTextDirectionDefaultsKey];
+  original_rtl_writing_direction_ =
+      [standard_defaults boolForKey:kForceRTLWritingDirectionDefaultsKey];
+  [standard_defaults setBool:YES forKey:kAppleTextDirectionDefaultsKey];
+  [standard_defaults setBool:YES forKey:kForceRTLWritingDirectionDefaultsKey];
+  original_locale_ = base::i18n::GetConfiguredLocale();
+  base::i18n::SetICUDefaultLocale(kDefaultRTLLocale);
+}
+
+ScopedForceRTLMac::~ScopedForceRTLMac() {
+  [[NSUserDefaults standardUserDefaults]
+      setBool:original_apple_text_direction_
+       forKey:kAppleTextDirectionDefaultsKey];
+  [[NSUserDefaults standardUserDefaults]
+      setBool:original_rtl_writing_direction_
+       forKey:kForceRTLWritingDirectionDefaultsKey];
+  base::i18n::SetICUDefaultLocale(original_locale_);
+}
+
+}  // namespace cocoa_l10n_util