Enable settings hardening on OSX when no Finch config is present

BUG=500085

Review-Url: https://codereview.chromium.org/2805923002
Cr-Commit-Position: refs/heads/master@{#463313}
diff --git a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
index ec497040..3236587 100644
--- a/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
+++ b/chrome/browser/prefs/tracked/pref_hash_browsertest.cc
@@ -417,9 +417,9 @@
 // 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;