Topsites become keyedService based.

chrome/browser/history/top_sites_factory.h

+// Copyright 2015 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_HISTORY_TOP_SITES_FACTORY_H_
+#define CHROME_BROWSER_HISTORY_TOP_SITES_FACTORY_H_
+
+#include "base/memory/ref_counted.h"
+#include "components/keyed_service/content/refcounted_browser_context_keyed_service_factory.h"
+
+class Profile;
+
+namespace history {
+class TopSites;
+}
+
+template <typename T>
+struct DefaultSingletonTraits;
+
+// Used for creating and fetching a per-profile instance of the
+// TopSites.
+class TopSitesFactory : public RefcountedBrowserContextKeyedServiceFactory {
+ public:
+  // Get the TopSites service for |profile|, creating one if needed.
+  static scoped_refptr<history::TopSites> GetForProfile(Profile* profile);
+
+  // Get the TopSites service for |profile|, but do not create it if it doesn't
+  // exist.
+  static scoped_refptr<history::TopSites> GetForProfileIfExists(
+      Profile* profile);
+
+  // Get the singleton instance of the factory.
+  static TopSitesFactory* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<TopSitesFactory>;
+
+  TopSitesFactory();
+  ~TopSitesFactory() override;
+
+  // Overridden from BrowserContextKeyedServiceFactory.
+  scoped_refptr<RefcountedKeyedService> BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+  bool ServiceIsNULLWhileTesting() const override;
+
+  DISALLOW_COPY_AND_ASSIGN(TopSitesFactory);
+};
+
+#endif  // CHROME_BROWSER_HISTORY_TOP_SITES_FACTORY_H_