[Password Manager] Add UMA stats for custom passphrase users.

chrome/browser/password_manager/test_password_store_service.cc

 // Copyright 2014 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 "chrome/browser/password_manager/test_password_store_service.h"
 
 #include "components/password_manager/core/browser/test_password_store.h"
 
 // static
 KeyedService* TestPasswordStoreService::Build(
     content::BrowserContext* /*profile*/) {
   scoped_refptr<password_manager::PasswordStore> store(
       new password_manager::TestPasswordStore);
-  if (!store.get() ||
-      !store->Init(syncer::SyncableService::StartSyncFlare(), ""))
+  if (!store.get() || !store->Init(syncer::SyncableService::StartSyncFlare()))
     return NULL;
   return new TestPasswordStoreService(store);
 }
 
 TestPasswordStoreService::TestPasswordStoreService(
     scoped_refptr<password_manager::PasswordStore> password_store)
     : PasswordStoreService(password_store) {}
 
 TestPasswordStoreService::~TestPasswordStoreService() {}