Add prefs for ContentSuggestions on iOS

ios/chrome/browser/prefs/browser_prefs.mm

Index: ios/chrome/browser/prefs/browser_prefs.mm
diff --git a/ios/chrome/browser/prefs/browser_prefs.mm b/ios/chrome/browser/prefs/browser_prefs.mm
index 8b9f604d124aab9c91c3ac93a53c50ba961246b0..c39b4241e3d8acee511ea23baf06836edaf24182 100644
--- a/ios/chrome/browser/prefs/browser_prefs.mm
+++ b/ios/chrome/browser/prefs/browser_prefs.mm
@@ -14,9 +14,12 @@
 #include "components/metrics/metrics_pref_names.h"
 #include "components/network_time/network_time_tracker.h"
 #include "components/ntp_snippets/bookmarks/bookmark_suggestions_provider.h"
+#include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 #include "components/ntp_snippets/content_suggestions_service.h"
 #include "components/ntp_snippets/remote/remote_suggestions_provider_impl.h"
+#include "components/ntp_snippets/remote/request_throttler.h"
 #include "components/ntp_snippets/remote/scheduling_remote_suggestions_provider.h"
+#include "components/ntp_snippets/user_classifier.h"
 #include "components/ntp_tiles/most_visited_sites.h"
 #include "components/ntp_tiles/popular_sites_impl.h"
 #include "components/omnibox/browser/zero_suggest_provider.h"
@@ -94,10 +97,13 @@ void RegisterBrowserStatePrefs(user_prefs::PrefRegistrySyncable* registry) {
   HostContentSettingsMap::RegisterProfilePrefs(registry);
   HttpServerPropertiesManagerFactory::RegisterProfilePrefs(registry);
   ntp_snippets::BookmarkSuggestionsProvider::RegisterProfilePrefs(registry);
+  ntp_snippets::ClickBasedCategoryRanker::RegisterProfilePrefs(registry);
   ntp_snippets::ContentSuggestionsService::RegisterProfilePrefs(registry);
   ntp_snippets::RemoteSuggestionsProviderImpl::RegisterProfilePrefs(registry);
+  ntp_snippets::RequestThrottler::RegisterProfilePrefs(registry);
   ntp_snippets::SchedulingRemoteSuggestionsProvider::RegisterProfilePrefs(
       registry);
+  ntp_snippets::UserClassifier::RegisterProfilePrefs(registry);
   ntp_tiles::MostVisitedSites::RegisterProfilePrefs(registry);
   ntp_tiles::PopularSitesImpl::RegisterProfilePrefs(registry);
   ios::NotificationPromo::RegisterProfilePrefs(registry);