Get rid of the ability to unregister preferences.

chrome/browser/prefs/browser_prefs.cc

 // Copyright 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 "chrome/browser/prefs/browser_prefs.h"
 
 #include "apps/prefs.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/about_flags.h"
@@ skipping 97 matching lines @@
 #if defined(TOOLKIT_GTK)
 #include "chrome/browser/ui/gtk/browser_window_gtk.h"
 #endif
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/app_mode/kiosk_app_manager.h"
 #include "chrome/browser/chromeos/audio/audio_handler.h"
 #include "chrome/browser/chromeos/customization_document.h"
 #include "chrome/browser/chromeos/display/display_preferences.h"
 #include "chrome/browser/chromeos/login/login_utils.h"
+#include "chrome/browser/chromeos/login/oauth2_login_manager.h"
 #include "chrome/browser/chromeos/login/user_image_manager.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/chromeos/login/wallpaper_manager.h"
 #include "chrome/browser/chromeos/login/wizard_controller.h"
 #include "chrome/browser/chromeos/preferences.h"
 #include "chrome/browser/chromeos/proxy_config_service_impl.h"
 #include "chrome/browser/chromeos/settings/device_settings_cache.h"
 #include "chrome/browser/chromeos/status/data_promo_notification.h"
 #include "chrome/browser/policy/auto_enrollment_client.h"
 #include "chrome/browser/policy/device_cloud_policy_manager_chromeos.h"
@@ skipping 20 matching lines @@
 
 namespace {
 
 enum MigratedPreferences {
   NO_PREFS = 0,
   DNS_PREFS = 1 << 0,
   WINDOWS_PREFS = 1 << 1,
   GOOGLE_URL_TRACKER_PREFS = 1 << 2,
 };
 
+// Name of an old pref that is cleared in MigrateUserPrefs.

[Mattias Nissler (ping if slow), 2013/02/20 17:17:27]

I think it'd be nicer to actually have this in pref_names.h for consistency
(i.e. restore the old pref definition that I hope was there originally for
whoever used this). Might require some digging in history, but will probably
reduce the WTF-factor for readers.

[Jói, 2013/02/21 12:05:10]

This wasn't in pref_names, it was in a .cc file that has been removed. I added a
comment with further explanation of what this pref name is, and referencing the
removed file so people can dig through history if they like.

+const char kBackupPref[] = "backup";
+
 }  // namespace
 
 namespace chrome {
 
 void RegisterLocalState(PrefRegistrySimple* registry) {
   // Prefs in Local State.
   registry->RegisterIntegerPref(prefs::kMultipleProfilePrefMigration, 0);
 
   // Please keep this list alphabetized.
   apps::RegisterPrefs(registry);
@@ skipping 162 matching lines @@
   printing::StickySettings::RegisterUserPrefs(registry);
   RegisterAutolaunchUserPrefs(registry);
   SyncPromoUI::RegisterUserPrefs(registry);
 #endif
 
 #if !defined(OS_ANDROID) && !defined(OS_CHROMEOS)
   default_apps::RegisterUserPrefs(registry);
 #endif
 
 #if defined(OS_CHROMEOS)
+  chromeos::OAuth2LoginManager::RegisterUserPrefs(registry);
   chromeos::Preferences::RegisterUserPrefs(registry);
   chromeos::ProxyConfigServiceImpl::RegisterUserPrefs(registry);
 #endif
 
 #if defined(OS_WIN)
   NetworkProfileBubble::RegisterUserPrefs(registry);
 #endif
+
+  // Prefs registered only for migration (clearing or moving to a new
+  // key) go here.
+  registry->RegisterDictionaryPref(kBackupPref, new DictionaryValue(),
+                                   PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 void MigrateUserPrefs(Profile* profile) {
+  PrefService* prefs = profile->GetPrefs();
+
   // Cleanup old prefs.
-  static const char kBackupPref[] = "backup";
-  PrefService* prefs = profile->GetPrefs();
-  // TODO(joi): Fix to not require post-construction registration?
-  scoped_refptr<PrefRegistrySyncable> registry(
-      static_cast<PrefRegistrySyncable*>(prefs->DeprecatedGetPrefRegistry()));
-  registry->RegisterDictionaryPref(kBackupPref, new DictionaryValue(),
-                                   PrefRegistrySyncable::UNSYNCABLE_PREF);
   prefs->ClearPref(kBackupPref);
-  registry->DeprecatedUnregisterPreference(kBackupPref);
 
-  PrefsTabHelper::MigrateUserPrefs(prefs, registry);
+  PrefsTabHelper::MigrateUserPrefs(prefs);
 }
 
 void MigrateBrowserPrefs(Profile* profile, PrefService* local_state) {
   // Copy pref values which have been migrated to user_prefs from local_state,
   // or remove them from local_state outright, if copying is not required.
   int current_version =
       local_state->GetInteger(prefs::kMultipleProfilePrefMigration);
   PrefRegistrySimple* registry = static_cast<PrefRegistrySimple*>(
       local_state->DeprecatedGetPrefRegistry());
 
@@ skipping 53 matching lines @@
     }
     local_state->ClearPref(prefs::kLastPromptedGoogleURL);
 
     current_version |= GOOGLE_URL_TRACKER_PREFS;
     local_state->SetInteger(prefs::kMultipleProfilePrefMigration,
                             current_version);
   }
 }
 
 }  // namespace chrome