[Mac] Don't flip window controls in RTL for macOS < 10.12

chrome/browser/ui/cocoa/l10n_util.h

Index: chrome/browser/ui/cocoa/l10n_util.h
diff --git a/chrome/browser/ui/cocoa/l10n_util.h b/chrome/browser/ui/cocoa/l10n_util.h
index fcf68d99634379baa24d16970b50a7c17b9f5b6d..a7d8a8069652f35ec6f90a85f348fb7419e0b50c 100644
--- a/chrome/browser/ui/cocoa/l10n_util.h
+++ b/chrome/browser/ui/cocoa/l10n_util.h
@@ -43,4 +43,10 @@ extern const base::Feature kExperimentalMacRTL;
 // uses of base::i18n::IsRTL().
 bool ShouldDoExperimentalRTLLayout();
 
+// Returns true if ShouldDoExperimentalRTLLayout() is true and the OS is
+// 10.12 or above. macOS 10.12 is the first OS where the native stoplight
+// buttons are reversed in RTL, so manually reversing them in previous
+// OSes would make Chrome stick out.
+bool ShouldFlipWindowControlsInRTL();
+
 }  // namespace cocoa_l10n_util