Componentize TopSites, TopSitesBackend, TopSitesDatabase

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;
 
+namespace history {
+class TopSites;
+}
+
+class Profile;
+
 // 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(
@@ skipping 10 matching lines @@
 
   // 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_