Enable settings hardening on OSX when no Finch config is present

chrome/browser/prefs/tracked/pref_hash_browsertest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 #include <string>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 397 matching lines @@
 
   SettingsProtectionLevel GetProtectionLevelFromTrialGroup(
       const std::string& trial_group) {
     if (!ProfilePrefStoreManager::kPlatformSupportsPreferenceTracking)
       return PROTECTION_DISABLED_ON_PLATFORM;
 
 // Protection levels can't be adjusted via --force-fieldtrials in official
 // 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;
 #endif
 
 #else  // defined(OFFICIAL_BUILD)
 
     using namespace chrome_prefs::internals;
     if (trial_group == kSettingsEnforcementGroupNoEnforcement) {
       return PROTECTION_DISABLED_FOR_GROUP;
@@ skipping 840 matching lines @@
       EXPECT_EQ(DefaultSearchManager::FROM_FALLBACK, dse_source);
       EXPECT_NE(current_dse->keyword(), base::UTF8ToUTF16("badkeyword"));
       EXPECT_NE(current_dse->short_name(), base::UTF8ToUTF16("badname"));
       EXPECT_NE(current_dse->url(),
                 "http://bad_default_engine/search?q=dirty_user_query");
     }
   }
 };
 
 PREF_HASH_BROWSER_TEST(PrefHashBrowserTestDefaultSearch, SearchProtected);