Clean up old legacy preference migration logic.

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 <string>
 
 #include "base/files/file_util.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 305 matching lines @@
 
 namespace chrome {
 
 void RegisterLocalState(PrefRegistrySimple* registry) {
   // Please keep this list alphabetized.
   AppListService::RegisterPrefs(registry);
   browser_shutdown::RegisterPrefs(registry);
   BrowserProcessImpl::RegisterPrefs(registry);
   ChromeMetricsServiceClient::RegisterPrefs(registry);
   ChromeTracingDelegate::RegisterPrefs(registry);
-  chrome_prefs::RegisterPrefs(registry);
   variations::VariationsService::RegisterPrefs(registry);
   component_updater::RegisterPrefsForRecoveryComponent(registry);
   component_updater::SupervisedUserWhitelistInstaller::RegisterPrefs(registry);
   ExternalProtocolHandler::RegisterPrefs(registry);
   flags_ui::PrefServiceFlagsStorage::RegisterPrefs(registry);
   geolocation::RegisterPrefs(registry);
   GLStringManager::RegisterPrefs(registry);
   GpuModeManager::RegisterPrefs(registry);
   IntranetRedirectDetector::RegisterPrefs(registry);
   IOThread::RegisterPrefs(registry);
@@ skipping 390 matching lines @@
   profile_prefs->ClearPref(kCheckDefaultBrowser);
 
   // Added 5/2016.
   profile_prefs->ClearPref(kDesktopSearchRedirectionInfobarShownPref);
 
   // Added 7/2016.
   DeleteWebRTCIdentityStoreDB(profile);
 }
 
 }  // namespace chrome