Adding an IO Data and keyed service to previews/

chrome/browser/previews/previews_service.cc

Index: chrome/browser/previews/previews_service.cc
diff --git a/chrome/browser/previews/previews_service.cc b/chrome/browser/previews/previews_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..62bec2466cc1c8f25f5cf2f91ab6da799ae05f71
--- /dev/null
+++ b/chrome/browser/previews/previews_service.cc
@@ -0,0 +1,27 @@
+// 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 "chrome/browser/previews/previews_service.h"
+
+#include "components/previews/previews_ui_service.h"
+#include "content/public/browser/browser_thread.h"
+
+PreviewsService::PreviewsService() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+}
+
+PreviewsService::~PreviewsService() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+}
+
+void PreviewsService::set_previews_ui_service(

[bengr, 2016/09/08 00:19:09]

You should be able to inline both the getter and setter.

[RyanSturm, 2016/09/08 18:34:33]

I'm not so sure about the setter, it would at least need to know that
PreviewsUIService has a public destructor, which forward declaring makes
uncertain, so I'll only move the getter.

+    std::unique_ptr<previews::PreviewsUIService> previews_ui_service) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  previews_ui_service_ = std::move(previews_ui_service);
+}
+
+previews::PreviewsUIService* PreviewsService::previews_ui_service() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  return previews_ui_service_.get();
+}