Adding an IO Data and keyed service to previews/

components/previews/previews_ui_service.cc

+// Copyright 2016 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/previews/previews_ui_service.h"
+
+#include "components/previews/previews_io_data.h"
+
+namespace previews {
+
+PreviewsUIService::PreviewsUIService(
+    PreviewsIOData* previews_io_data,
+    const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner)
+    : io_task_runner_(io_task_runner), weak_factory_(this) {
+  previews_io_data->Initialize(weak_factory_.GetWeakPtr());
+}
+
+PreviewsUIService::~PreviewsUIService() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void PreviewsUIService::SetIOData(base::WeakPtr<PreviewsIOData> io_data) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  io_data_ = io_data;
+}
+
+}  // namespace previews