Add a Model to the download component.

components/download/internal/noop_store.cc

Index: components/download/internal/noop_store.cc
diff --git a/components/download/internal/noop_store.cc b/components/download/internal/noop_store.cc
new file mode 100644
index 0000000000000000000000000000000000000000..42785cbc5b191709ce78182dc5565882fc269c1f
--- /dev/null
+++ b/components/download/internal/noop_store.cc
@@ -0,0 +1,53 @@
+// 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(InitCallback callback) {
+  DCHECK(!IsInitialized());
+
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::BindOnce(&NoopStore::OnInitFinished, weak_ptr_factory_.GetWeakPtr(),
+                     std::move(callback)));
+}
+
+void NoopStore::Destroy(StoreCallback callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(callback), true /** success */));
+}
+
+void NoopStore::Update(const Entry& entry, StoreCallback callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(callback), true /** success */));
+}
+
+void NoopStore::Remove(const std::string& guid, StoreCallback callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(callback), true /** success */));
+}
+
+void NoopStore::OnInitFinished(InitCallback callback) {
+  initialized_ = true;
+
+  std::unique_ptr<std::vector<Entry>> entries =
+      base::MakeUnique<std::vector<Entry>>();
+  std::move(callback).Run(true /** success */, std::move(entries));
+}
+
+}  // namespace download