Add a Model to the download component.

components/download/internal/noop_store.cc

+// Copyright 2017 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 "components/download/internal/noop_store.h"
+
+#include "base/bind.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "components/download/internal/entry.h"
+
+namespace download {
+
+NoopStore::NoopStore() : initialized_(false), weak_ptr_factory_(this) {}
+
+NoopStore::~NoopStore() = default;
+
+bool NoopStore::IsInitialized() {
+  return initialized_;
+}
+
+void NoopStore::Initialize(const InitCallback& callback) {
+  DCHECK(!IsInitialized());
+
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&NoopStore::OnInitFinished,
+                            weak_ptr_factory_.GetWeakPtr(), callback));
+}
+
+void NoopStore::Destroy(const StoreCallback& callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, true /** success */));
+}
+
+void NoopStore::Update(const Entry& entry, const StoreCallback& callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, true /** success */));
+}
+
+void NoopStore::Remove(const std::string& guid, const StoreCallback& callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, true /** success */));
+}
+
+void NoopStore::OnInitFinished(const InitCallback& callback) {
+  initialized_ = true;
+
+  std::unique_ptr<std::vector<Entry>> entries =
+      base::MakeUnique<std::vector<Entry>>();
+  callback.Run(true /** success */, std::move(entries));
+}
+
+}  // namespace download