Implement PasswordStoreProxyMac and SimplePasswordStoreMac.

chrome/browser/password_manager/simple_password_store_mac.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 "chrome/browser/password_manager/simple_password_store_mac.h"
+
+SimplePasswordStoreMac::SimplePasswordStoreMac(
+    scoped_refptr<base::SingleThreadTaskRunner> main_thread_runner,
+    scoped_refptr<base::SingleThreadTaskRunner> background_thread_runner,
+    scoped_ptr<password_manager::LoginDatabase> login_db)
+    : PasswordStoreDefault(main_thread_runner, nullptr, login_db.Pass()),

[Garrett Casto, 2015/06/22 08:24:08]

I'm not sure I understand what you are doing with the threading model here. It
looks like |background_thread_runner| to PasswordStoreDefault would give the
same behavior as you get from passing |nullptr| and overriding
GetBackgroundTaskRunner(). What am I missing here?

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

Yes. I was experimenting with clearing |background_thread_runner_| earlier.

+      background_thread_runner_(background_thread_runner) {
+  this->login_db()->set_clear_password_values(false);
+}
+
+SimplePasswordStoreMac::~SimplePasswordStoreMac() {
+}
+
+bool SimplePasswordStoreMac::Init(
+    const syncer::SyncableService::StartSyncFlare& flare) {
+  // All the initialization has to be done by the owner of the object.

[Garrett Casto, 2015/06/22 08:24:08]

This doesn't seem to agree with PasswordStoreProxyMac(), which just tries to
call Init() on it's backend. Are you planning on treating Init() specially for
some reason?

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

Yes. PasswordStoreProxyMac instantiate only PasswordStoreMac for now. In the
future patches PasswordStoreProxyMac::Init should be smarter.
SimplePasswordStoreMac::Init can be called after migration. The database and the
background thread are already inited. Therefore SimplePasswordStoreMac::Init
should be a noop.

+  return true;
+}
+
+void SimplePasswordStoreMac::Shutdown() {
+  PasswordStoreDefault::Shutdown();
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+SimplePasswordStoreMac::GetBackgroundTaskRunner() {
+  return background_thread_runner_;
+}