Make TopSites a RefcountedKeyedService

chrome/browser/history/chrome_history_client.h

 // Copyright 2014 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_CHROME_HISTORY_CLIENT_H_
 #define CHROME_BROWSER_HISTORY_CHROME_HISTORY_CLIENT_H_
 
 #include "base/macros.h"
 #include "components/history/core/browser/history_client.h"
 
-class HistoryService;
-class Profile;
-
 namespace bookmarks {
 class BookmarkModel;
 }
 
 // This class implements history::HistoryClient to abstract operations that
 // depend on Chrome environment.
 class ChromeHistoryClient : public history::HistoryClient {
  public:
   explicit ChromeHistoryClient(bookmarks::BookmarkModel* bookmark_model);
   ~ChromeHistoryClient() override;
 
   // history::HistoryClient:
   void BlockUntilBookmarksLoaded() override;
   bool IsBookmarked(const GURL& url) override;
   void GetBookmarks(std::vector<history::URLAndTitle>* bookmarks) override;
   void NotifyProfileError(sql::InitStatus init_status) override;
   bool ShouldReportDatabaseError() override;
 
   // KeyedService:
   void Shutdown() override;
 
  private:
   // The BookmarkModel, this should outlive ChromeHistoryClient.
   bookmarks::BookmarkModel* bookmark_model_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeHistoryClient);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_CHROME_HISTORY_CLIENT_H_