Only Register() platform specific content settings types on different platforms

components/content_settings/core/browser/host_content_settings_map.cc

 // Copyright (c) 2012 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 "components/content_settings/core/browser/host_content_settings_map.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 153 matching lines @@
   // wouldn't be needed except that we used to allow settings to be stored for
   // the guest profile and so we need to ensure those get cleared.
   if (is_guest_profile)
     pref_provider_->ClearPrefs();
 
   content_settings::ObservableProvider* default_provider =
       new content_settings::DefaultProvider(prefs_, is_off_the_record_);
   default_provider->AddObserver(this);
   content_settings_providers_[DEFAULT_PROVIDER] = default_provider;
 
+// ios doesn't have KEYGEN to be migrated.
+#if !defined(OS_IOS)

[msramek, 2016/05/23 14:49:49]

To make sure this stays in sync, could we just check if ->Get() == nullptr
inside the method itself?

[lshang, 2016/05/24 11:55:46]

Done.

   MigrateOldSettings();
-
+#endif
   RecordNumberOfExceptions();
 }
 
 // static
 void HostContentSettingsMap::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   // Ensure the content settings are all registered.
   content_settings::ContentSettingsRegistry::GetInstance();
 
   registry->RegisterIntegerPref(prefs::kContentSettingsWindowLastTabIndex, 0);
@@ skipping 676 matching lines @@
         rule.secondary_pattern.Matches(secondary_url)) {
       if (primary_pattern)
         *primary_pattern = rule.primary_pattern;
       if (secondary_pattern)
         *secondary_pattern = rule.secondary_pattern;
       return base::WrapUnique(rule.value.get()->DeepCopy());
     }
   }
   return std::unique_ptr<base::Value>();
 }