Convert Pass()→std::move() for iOS build.

ios/chrome/browser/prefs/ios_chrome_pref_service_factory.cc

 // 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/ios_chrome_pref_service_factory.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 50 matching lines @@
   // the preference store however since Chrome on iOS does not need to track
   // preference modifications (as applications are sand-boxed), it can use a
   // simple JsonPrefStore to store them (which is what PrefStoreManager uses
   // on platforms that do not track preference modifications).
   syncable_prefs::PrefServiceSyncableFactory factory;
   PrepareFactory(&factory, browser_state_path.Append(kPreferencesFilename),
                  pref_io_task_runner);
   scoped_ptr<syncable_prefs::PrefServiceSyncable> pref_service =
       factory.CreateSyncable(pref_registry.get());
   ConfigureDefaultSearchPrefMigrationToDictionaryValue(pref_service.get());
-  return pref_service.Pass();
+  return pref_service;
 }
 
 scoped_ptr<syncable_prefs::PrefServiceSyncable>
 CreateIncognitoBrowserStatePrefs(
     syncable_prefs::PrefServiceSyncable* pref_service) {
   // List of keys that cannot be changed in the user prefs file by the incognito
   // browser state. All preferences that store information about the browsing
   // history or behaviour of the user should have this property.
   std::vector<const char*> overlay_pref_names;
   overlay_pref_names.push_back(proxy_config::prefs::kProxy);
   return make_scoped_ptr(pref_service->CreateIncognitoPrefService(
       nullptr,  // incognito_extension_pref_store
       overlay_pref_names));
 }