Get rid of the ability to unregister preferences.

chrome/browser/ui/prefs/prefs_tab_helper.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 "chrome/browser/ui/prefs/prefs_tab_helper.h"
 
 #include <string>
 
 #include "base/prefs/overlay_user_pref_store.h"
 #include "base/prefs/pref_service.h"
@@ skipping 558 matching lines @@
       PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterLocalizedBooleanPref(prefs::kWebKitUsesUniversalDetector,
                                          IDS_USES_UNIVERSAL_DETECTOR,
                                          PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterLocalizedStringPref(prefs::kStaticEncodings,
                                         IDS_STATIC_ENCODING_LIST,
                                         PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterStringPref(prefs::kRecentlySelectedEncoding,
                                "",
                                PrefRegistrySyncable::UNSYNCABLE_PREF);
+
+  RegisterPrefsToMigrate(registry);
 }
 
-void PrefsTabHelper::MigrateUserPrefs(PrefService* prefs,
-                                      PrefRegistrySyncable* registry) {
-  RegisterPrefsToMigrate(registry);
+void PrefsTabHelper::MigrateUserPrefs(PrefService* prefs) {
   for (int i = 0; i < kPrefsToMigrateLength; ++i) {
     const PrefService::Preference* pref =
         prefs->FindPreference(kPrefNamesToMigrate[i].from);
-    if (!pref) continue;
-    if (!pref->IsDefaultValue()) {
+    if (pref && !pref->IsDefaultValue()) {
       prefs->Set(kPrefNamesToMigrate[i].to, *pref->GetValue());
+      prefs->ClearPref(kPrefNamesToMigrate[i].from);
     }
-    prefs->ClearPref(kPrefNamesToMigrate[i].from);
-    registry->DeprecatedUnregisterPreference(kPrefNamesToMigrate[i].from);
   }
 }
 
 void PrefsTabHelper::Observe(int type,
                              const content::NotificationSource& source,
                              const content::NotificationDetails& details) {
   switch (type) {
     case chrome::NOTIFICATION_USER_STYLE_SHEET_UPDATED:
       UpdateWebPreferences();
       break;
@@ skipping 53 matching lines @@
       WebPreferences web_prefs =
           web_contents_->GetRenderViewHost()->GetWebkitPreferences();
       OverrideFontFamily(&web_prefs, generic_family, script, "");
       web_contents_->GetRenderViewHost()->UpdateWebkitPreferences(web_prefs);
       return;
     }
   }
 
   UpdateWebPreferences();
 }