Pref service: enable for user prefs in chrome behind a flag.

components/sync_preferences/pref_service_syncable_factory.cc

 // Copyright 2013 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 "components/sync_preferences/pref_service_syncable_factory.h"
 
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/default_pref_store.h"
@@ skipping 46 matching lines @@
 
 namespace {
 
 // Expose the |backing_pref_store| through the prefs service.
 scoped_refptr<::PrefStore> CreateRegisteredPrefStore(
     service_manager::Connector* connector,
     scoped_refptr<::PrefStore> backing_pref_store,
     PrefValueStore::PrefStoreType type) {
   // If we're testing or if the prefs service feature flag is off we don't
   // register.
-  if (!connector)
+  if (!connector || !backing_pref_store)
     return backing_pref_store;
 
   prefs::mojom::PrefStoreRegistryPtr registry_ptr;
   connector->BindInterface(prefs::mojom::kPrefStoreServiceName, &registry_ptr);
   return make_scoped_refptr(new prefs::PrefStoreAdapter(
       backing_pref_store,
       prefs::PrefStoreImpl::Create(std::move(registry_ptr), backing_pref_store,
                                    type)));
 }
 
@@ skipping 23 matching lines @@
       new PrefValueStore(managed.get(), supervised.get(), extension.get(),
                          command_line.get(), user_prefs_.get(),
                          recommended.get(), pref_registry->defaults().get(),
                          pref_notifier),
       user_prefs_.get(), pref_registry, pref_model_associator_client_,
       read_error_callback_, async_));
   return pref_service;
 }
 
 }  // namespace sync_preferences