Componentize TopSites, TopSitesBackend, TopSitesDatabase

components/history/core/browser/top_sites_backend.h

 // Copyright (c) 2011 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_BACKEND_H_
-#define CHROME_BROWSER_HISTORY_TOP_SITES_BACKEND_H_
+#ifndef COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_
+#define COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/history/core/browser/history_types.h"
 
 namespace base {
 class CancelableTaskTracker;
 class FilePath;
+class SingleThreadTaskRunner;
 }
 
 namespace history {
 
 class TopSitesDatabase;
 
 // Service used by TopSites to have db interaction happen on the DB thread.  All
 // public methods are invoked on the ui thread and get funneled to the DB
 // thread.
 class TopSitesBackend : public base::RefCountedThreadSafe<TopSitesBackend> {
  public:
   // The boolean parameter indicates if the DB existed on disk or needs to be
   // migrated.
   typedef base::Callback<void(const scoped_refptr<MostVisitedThumbnails>&)>
       GetMostVisitedThumbnailsCallback;
 
-  TopSitesBackend();
+  explicit TopSitesBackend(
+      const scoped_refptr<base::SingleThreadTaskRunner>& db_task_runner);
 
   void Init(const base::FilePath& path);
 
   // Schedules the db to be shutdown.
   void Shutdown();
 
   // Fetches MostVisitedThumbnails.
   void GetMostVisitedThumbnails(
       const GetMostVisitedThumbnailsCallback& callback,
       base::CancelableTaskTracker* tracker);
@@ skipping 11 matching lines @@
 
   // Schedules a request that does nothing on the DB thread, but then notifies
   // the the calling thread with a reply. This is used to make sure the db has
   // finished processing a request.
   void DoEmptyRequest(const base::Closure& reply,
                       base::CancelableTaskTracker* tracker);
 
  private:
   friend class base::RefCountedThreadSafe<TopSitesBackend>;
 
-  virtual ~TopSitesBackend();
+  ~TopSitesBackend();
 
   // Invokes Init on the db_.
   void InitDBOnDBThread(const base::FilePath& path);
 
   // Shuts down the db.
   void ShutdownDBOnDBThread();
 
   // Does the work of getting the most visted thumbnails.
   void GetMostVisitedThumbnailsOnDBThread(
       scoped_refptr<MostVisitedThumbnails> thumbnails);
 
   // Updates top sites.
   void UpdateTopSitesOnDBThread(const TopSitesDelta& delta);
 
   // Sets the thumbnail.
   void SetPageThumbnailOnDBThread(const MostVisitedURL& url,
                                   int url_rank,
                                   const Images& thumbnail);
 
   // Resets the database.
   void ResetDatabaseOnDBThread(const base::FilePath& file_path);
 
   base::FilePath db_path_;
 
   scoped_ptr<TopSitesDatabase> db_;
+  scoped_refptr<base::SingleThreadTaskRunner> db_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesBackend);
 };
 
 }  // namespace history
 
-#endif  // CHROME_BROWSER_HISTORY_TOP_SITES_BACKEND_H_
+#endif  // COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_