Add MacRTL feature to flags

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 1baf874366e65bed1fe18c6054fe33f30f1c49f1..f60db4e80c99396ac1b7800e5bfa5c48e485ec56 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2901,6 +2901,12 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_VALUE_TYPE(features::kOneGoogleBarOnLocalNtp)},
 #endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
 
+#if defined(OS_MACOSX)
+    {"mac-rtl", flag_descriptions::kMacRTLName,
+     flag_descriptions::kMacRTLDescription, kOsMac,
+     FEATURE_VALUE_TYPE(features::kMacRTL)},
+#endif  // defined(OS_MACOSX)
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms/enums.xml. See note in
     // enums.xml and don't forget to run AboutFlagsHistogramTest unit test.