Componentize TopSites, TopSitesBackend, TopSitesDatabase

chrome/browser/history/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_
-
-#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;
-}
-
-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();
-
-  void Init(const base::FilePath& path);
-
-  // Schedules the db to be shutdown.
-  void Shutdown();
-
-  // Fetches MostVisitedThumbnails.
-  void GetMostVisitedThumbnails(
-      const GetMostVisitedThumbnailsCallback& callback,
-      base::CancelableTaskTracker* tracker);
-
-  // Updates top sites database from the specified delta.
-  void UpdateTopSites(const TopSitesDelta& delta);
-
-  // Sets the thumbnail.
-  void SetPageThumbnail(const MostVisitedURL& url,
-                        int url_rank,
-                        const Images& thumbnail);
-
-  // Deletes the database and recreates it.
-  void ResetDatabase();
-
-  // 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();
-
-  // 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_;
-
-  DISALLOW_COPY_AND_ASSIGN(TopSitesBackend);
-};
-
-}  // namespace history
-
-#endif  // CHROME_BROWSER_HISTORY_TOP_SITES_BACKEND_H_