[Mac] Reverse bookmark bar overflow chevron in RTL

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm

 // Copyright (c) 2012 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.
 
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.h"
 
 #include <stddef.h>
 
 #import "base/mac/bundle_locations.h"
 #import "base/mac/foundation_util.h"
@@ skipping 846 matching lines @@
 }
 
 - (NSButton*)offTheSideButton {
   return offTheSideButton_;
 }
 
 - (NSImage*)offTheSideButtonImage:(BOOL)forDarkMode {
   const int kIconSize = 8;
   SkColor vectorIconColor = forDarkMode ? SkColorSetA(SK_ColorWHITE, 0xCC)
                                         : gfx::kChromeIconGrey;
-  return NSImageFromImageSkia(
+  NSImage* image = NSImageFromImageSkia(
       gfx::CreateVectorIcon(kOverflowChevronIcon, kIconSize, vectorIconColor));
+  if (cocoa_l10n_util::ShouldDoExperimentalRTLLayout())
+    return cocoa_l10n_util::FlippedImage(image);
+  else
+    return image;
 }
 
 #pragma mark Private Methods
 
 // Called after a theme change took place, possibly for a different profile.
 - (void)themeDidChangeNotification:(NSNotification*)notification {
   [self updateTheme:[[[self view] window] themeProvider]];
 }
 
 - (BookmarkLaunchLocation)bookmarkLaunchLocation {
@@ skipping 1785 matching lines @@
     return self;
   return [folderController_ controllerForNode:node];
 }
 
 // For testing.
 - (const BookmarkBarLayout&)currentLayout {
   return layout_;
 }
 
 @end