Add ScopedMacRTL class for Cocoa browser RTL testing

chrome/browser/ui/cocoa/new_tab_button.mm

Index: chrome/browser/ui/cocoa/new_tab_button.mm
diff --git a/chrome/browser/ui/cocoa/new_tab_button.mm b/chrome/browser/ui/cocoa/new_tab_button.mm
index 3224e675066a5b43bfe63928b6a36589320d1415..664346706f63b73f261081e56b478c43f8ad9ddf 100644
--- a/chrome/browser/ui/cocoa/new_tab_button.mm
+++ b/chrome/browser/ui/cocoa/new_tab_button.mm
@@ -7,10 +7,10 @@
 #include "base/mac/foundation_util.h"
 #include "base/mac/sdk_forward_declarations.h"
 #import "chrome/browser/ui/cocoa/image_button_cell.h"
-#include "chrome/browser/ui/cocoa/l10n_util.h"
 #include "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #include "chrome/grit/theme_resources.h"
 #include "ui/base/cocoa/nsgraphics_context_additions.h"
+#import "ui/base/cocoa/rtl_feature.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/theme_provider.h"
@@ -374,7 +374,7 @@ CGFloat LineWidthFromContext(CGContextRef context) {
   // The SVG path is flipped for some reason, so flip it back. However, in RTL,
   // we'd need to flip it again below, so when in RTL mode just leave the flip
   // out altogether.
-  if (!cocoa_l10n_util::ShouldDoExperimentalRTLLayout()) {
+  if (!ui::ShouldDoExperimentalRTLLayout()) {
     const CGFloat kSVGHeight = 32;
     NSAffineTransformStruct flipStruct = {1, 0, 0, -1, 0, kSVGHeight};
     NSAffineTransform* flipTransform = [NSAffineTransform transform];