[Mac] Reverse bookmark bar overflow chevron in RTL

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

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
index c41e17b73b26323794a16a4378fdf191baeff7cb..328e72ad15a5a25453b79ec88b68672355651554 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
@@ -864,8 +864,12 @@ bool operator!=(const BookmarkBarLayout& lhs, const BookmarkBarLayout& rhs) {
   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