Enable settings hardening on OSX when no Finch config is present

chrome/browser/prefs/chrome_pref_service_factory.cc

Index: chrome/browser/prefs/chrome_pref_service_factory.cc
diff --git a/chrome/browser/prefs/chrome_pref_service_factory.cc b/chrome/browser/prefs/chrome_pref_service_factory.cc
index 1e9b90229df9be9a8344347c2ff891c09d1c037e..6414063c2aa1901f9459adbd9dfff9adbcf144c1 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.cc
+++ b/chrome/browser/prefs/chrome_pref_service_factory.cc
@@ -230,12 +230,12 @@ SettingsEnforcementGroup GetSettingsEnforcementGroup() {
   };
 
   // Use the strongest enforcement setting in the absence of a field trial
-  // config on Windows. Remember to update the OFFICIAL_BUILD section of
-  // extension_startup_browsertest.cc and pref_hash_browsertest.cc when updating
-  // the default value below.
+  // config on Windows and MacOS. Remember to update the OFFICIAL_BUILD section
+  // of extension_startup_browsertest.cc and pref_hash_browsertest.cc when
+  // updating the default value below.
   // TODO(gab): Enforce this on all platforms.
   SettingsEnforcementGroup enforcement_group =
-#if defined(OS_WIN)
+#if defined(OS_WIN) || defined(OS_MACOSX)
       GROUP_ENFORCE_DEFAULT;
 #else
       GROUP_NO_ENFORCEMENT;