[Hotword] Putting preferences under search for hotword service. Putting behind a flag.

chrome/browser/search/hotword_service_factory.cc

Index: chrome/browser/search/hotword_service_factory.cc
diff --git a/chrome/browser/search/hotword_service_factory.cc b/chrome/browser/search/hotword_service_factory.cc
index 675d86c24d4c6bcad392e1e20abca312a53ab473..ce3ed2fec7ef027d6236c23de68e4406ef1fb1d1 100644
--- a/chrome/browser/search/hotword_service_factory.cc
+++ b/chrome/browser/search/hotword_service_factory.cc
@@ -46,6 +46,9 @@ void HotwordServiceFactory::RegisterProfilePrefs(
   prefs->RegisterBooleanPref(prefs::kHotwordSearchIncognitoEnabled,
                              false,
                              user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  prefs->RegisterBooleanPref(prefs::kHotwordSearchTimeoutEnabled,
+                             true,
+                             user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 content::BrowserContext* HotwordServiceFactory::GetBrowserContextToUse(