Adding an IO Data and keyed service to previews/

chrome/browser/previews/previews_service_factory.h

+// 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.
+
+#ifndef CHROME_BROWSER_PREVIEWS_PREVIEWS_SERVICE_FACTORY_H_
+#define CHROME_BROWSER_PREVIEWS_PREVIEWS_SERVICE_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class Profile;
+
+namespace content {
+class BrowserContext;
+}
+
+class PreviewsService;
+
+class PreviewsServiceFactory : public BrowserContextKeyedServiceFactory {

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

Add class comment and comments for public methods.

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

Done.

+ public:
+  static PreviewsService* GetForProfile(Profile* profile);
+
+  static PreviewsServiceFactory* GetInstance();
+
+ private:
+  friend struct base::DefaultSingletonTraits<PreviewsServiceFactory>;
+
+  PreviewsServiceFactory();
+  ~PreviewsServiceFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+};
+
+#endif  // CHROME_BROWSER_PREVIEWS_PREVIEWS_SERVICE_FACTORY_H_