Implement PasswordStoreProxyMac and SimplePasswordStoreMac.

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 "components/password_manager/core/browser/password_store_default.h"
+
+// 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:
+  SimplePasswordStoreMac(
+      scoped_refptr<base::SingleThreadTaskRunner> main_thread_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> background_thread_runner,
+      scoped_ptr<password_manager::LoginDatabase> login_db);
+
+  // Just hides the parent method. All the initialization is to be done by the
+  // proxy.

[vabr (Chromium), 2015/06/19 20:19:09]

nit: In this context, it is not clear what "the proxy" means. At the very least,
mention the full class name PasswordStoreProxy, optionally clarifying how the
proxy and the instance of SimplePasswordStoreMac are related.

[vasilii, 2015/06/22 13:34:17]

Done.

+  bool Init(const syncer::SyncableService::StartSyncFlare& flare) override;
+
+  // Clean |background_thread_runner_|.
+  void Shutdown() override;
+
+  scoped_refptr<base::SingleThreadTaskRunner> GetBackgroundTaskRunner()
+      override;
+
+ protected:
+  ~SimplePasswordStoreMac() override;
+
+ private:
+  scoped_refptr<base::SingleThreadTaskRunner> background_thread_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(SimplePasswordStoreMac);
+};
+
+#endif  // CHROME_BROWSER_PASSWORD_MANAGER_SIMPLE_PASSWORD_STORE_MAC_H_