Enable settings hardening on OSX when no Finch config is present

chrome/browser/prefs/tracked/pref_hash_browsertest.cc

Index: chrome/browser/prefs/tracked/pref_hash_browsertest.cc
diff --git a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
index 513998b727f277aae996165a606ddf5b53dd2be5..c3984980a848508ea676fd234c84a655e07efd12 100644
--- a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
+++ b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
@@ -415,9 +415,9 @@ class PrefHashBrowserTestBase
 // builds.
 #if defined(OFFICIAL_BUILD)
 
-#if defined(OS_WIN)
-    // The strongest mode is enforced on Windows in the absence of a field
-    // trial.
+#if defined(OS_WIN) || defined(OS_MACOSX)
+    // The strongest mode is enforced on Windows and MacOS in the absence of a
+    // field trial.
     return PROTECTION_ENABLED_ALL;
 #else
     return PROTECTION_DISABLED_FOR_GROUP;