Creating a preference for storing a sync password hash.

chrome/browser/password_manager/simple_password_store_mac.h

 // 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.
 
 #ifndef CHROME_BROWSER_PASSWORD_MANAGER_SIMPLE_PASSWORD_STORE_MAC_H_
 #define CHROME_BROWSER_PASSWORD_MANAGER_SIMPLE_PASSWORD_STORE_MAC_H_
 
 #include "base/macros.h"
 #include "components/password_manager/core/browser/password_store_default.h"
 
+class PrefService;
+
 // The same as PasswordStoreDefault but running on the dedicated thread. The
 // owner is responsible for the thread lifetime.
 class SimplePasswordStoreMac : public password_manager::PasswordStoreDefault {
  public:
   // Passes the arguments to PasswordStoreDefault. |background_task_runner| and
   // |login_db| can be overwritten later in InitWithTaskRunner().
   SimplePasswordStoreMac(
       scoped_refptr<base::SingleThreadTaskRunner> main_thread_runner,
       scoped_refptr<base::SingleThreadTaskRunner> background_thread_runner,
       std::unique_ptr<password_manager::LoginDatabase> login_db);
 
   // Sets the background thread and LoginDatabase. |login_db| should be already
   // inited. The method isn't necessary to call if the constructor already got
   // the correct parameters.
   void InitWithTaskRunner(
       scoped_refptr<base::SingleThreadTaskRunner> background_task_runner,
       std::unique_ptr<password_manager::LoginDatabase> login_db);
 
   using PasswordStoreDefault::GetBackgroundTaskRunner;
 
  protected:
   ~SimplePasswordStoreMac() override;
 
  private:
-  bool Init(const syncer::SyncableService::StartSyncFlare& flare) override;
+  bool Init(const syncer::SyncableService::StartSyncFlare& flare,
+            PrefService* prefs) override;
 
   DISALLOW_COPY_AND_ASSIGN(SimplePasswordStoreMac);
 };
 
 #endif  // CHROME_BROWSER_PASSWORD_MANAGER_SIMPLE_PASSWORD_STORE_MAC_H_