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"

[Lei Zhang, 2016/09/08 19:06:23]

Please read the top of singleton.h. Can you use a LazyInstance instead?

[RyanSturm, 2016/09/08 20:19:09]

Done.

[Lei Zhang, 2016/09/08 21:31:56]

Thanks. I realize someone implemented the first one with a Singleton and
everyone copied it...

+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class Profile;

[Lei Zhang, 2016/09/08 19:06:23]

Group this with the PreviewService fwrd decl.

[RyanSturm, 2016/09/08 20:19:09]

Done.

+
+namespace content {
+class BrowserContext;
+}
+
+class PreviewsService;
+
+// Singleton that owns all PreviewsServices and associates them with
+// Profiles.
+class PreviewsServiceFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  // Gets the PreviewsService instance for |profile|.
+  static PreviewsService* GetForProfile(Profile* profile);
+
+  // Gets the Singleton that owns all all PreviewsServices.
+  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_