[NTP Snippets] Persist the set of snippets in a pref

ios/chrome/browser/prefs/browser_prefs.mm

 // Copyright 2015 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 "ios/chrome/browser/prefs/browser_prefs.h"
 
 #include "components/autofill/core/browser/autofill_manager.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_prefs.h"
 #include "components/dom_distiller/core/distilled_page_prefs.h"
 #include "components/flags_ui/pref_service_flags_storage.h"
 #include "components/gcm_driver/gcm_channel_status_syncer.h"
 #include "components/network_time/network_time_tracker.h"
+#include "components/ntp_snippets/ntp_snippets_service.h"
 #include "components/omnibox/browser/zero_suggest_provider.h"
 #include "components/password_manager/core/browser/password_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "components/proxy_config/pref_proxy_config_tracker_impl.h"
 #include "components/rappor/rappor_service.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
 #include "components/signin/core/common/signin_pref_names.h"
 #include "components/ssl_config/ssl_config_service_manager.h"
 #include "components/strings/grit/components_locale_settings.h"
@@ skipping 54 matching lines @@
 }
 
 void RegisterBrowserStatePrefs(user_prefs::PrefRegistrySyncable* registry) {
   autofill::AutofillManager::RegisterProfilePrefs(registry);
   data_reduction_proxy::RegisterSyncableProfilePrefs(registry);
   dom_distiller::DistilledPagePrefs::RegisterProfilePrefs(registry);
   FirstRun::RegisterProfilePrefs(registry);
   gcm::GCMChannelStatusSyncer::RegisterProfilePrefs(registry);
   HostContentSettingsMap::RegisterProfilePrefs(registry);
   HttpServerPropertiesManagerFactory::RegisterProfilePrefs(registry);
+  ntp_snippets::NTPSnippetsService::RegisterProfilePrefs(registry);
   password_manager::PasswordManager::RegisterProfilePrefs(registry);
   PrefProxyConfigTrackerImpl::RegisterProfilePrefs(registry);
   sync_driver::SyncPrefs::RegisterProfilePrefs(registry);
   TemplateURLPrepopulateData::RegisterProfilePrefs(registry);
   translate::TranslatePrefs::RegisterProfilePrefs(registry);
   variations::VariationsService::RegisterProfilePrefs(registry);
   web_resource::PromoResourceService::RegisterProfilePrefs(registry);
   ZeroSuggestProvider::RegisterProfilePrefs(registry);
 
   registry->RegisterBooleanPref(prefs::kDataSaverEnabled, false);
@@ skipping 42 matching lines @@
 void MigrateObsoleteLocalStatePrefs(PrefService* prefs) {}
 
 // This method should be periodically pruned of year+ old migrations.
 void MigrateObsoleteBrowserStatePrefs(PrefService* prefs) {
   // Added 07/2014.
   translate::TranslatePrefs::MigrateUserPrefs(prefs, prefs::kAcceptLanguages);
 
   // Added 08/2015.
   prefs->ClearPref(::prefs::kSigninSharedAuthenticationUserId);
 }