Port History::QueryMostVisitedURLs to use CancelableTaskTracker

chrome/browser/history/history_service.h

 // Copyright (c) 2012 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_HISTORY_SERVICE_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 293 matching lines @@
   // to all urls on the same scheme/host/port as |url|.  This is only valid for
   // HTTP and HTTPS URLs.
   base::CancelableTaskTracker::TaskId GetVisibleVisitCountToHost(
       const GURL& url,
       const GetVisibleVisitCountToHostCallback& callback,
       base::CancelableTaskTracker* tracker);
 
   // Request the |result_count| most visited URLs and the chain of
   // redirects leading to each of these URLs. |days_back| is the
   // number of days of history to use. Used by TopSites.
-  typedef base::Callback<void(Handle, history::MostVisitedURLList)>
+  typedef base::Callback<void(const history::MostVisitedURLList*)>

[blundell, 2014/06/26 09:21:54]

I think that we avoid const pointers in Chromium, although I don't know the
reasoning as to why.

       QueryMostVisitedURLsCallback;
 
-  Handle QueryMostVisitedURLs(int result_count, int days_back,
-                              CancelableRequestConsumerBase* consumer,
-                              const QueryMostVisitedURLsCallback& callback);
+  base::CancelableTaskTracker::TaskId QueryMostVisitedURLs(
+      int result_count,
+      int days_back,
+      const QueryMostVisitedURLsCallback& callback,
+      base::CancelableTaskTracker* tracker);
 
   // Request the |result_count| URLs filtered and sorted based on the |filter|.
   // If |extended_info| is true, additional data will be provided in the
   // results. Computing this additional data is expensive, likely to become
   // more expensive as additional data points are added in future changes, and
   // not useful in most cases. Set |extended_info| to true only if you
   // explicitly require the additional data.
   typedef base::Callback<void(Handle, const history::FilteredURLList&)>
       QueryFilteredURLsCallback;
 
@@ skipping 685 matching lines @@
   scoped_ptr<history::InMemoryURLIndex> in_memory_url_index_;
 
   ObserverList<history::VisitDatabaseObserver> visit_database_observers_;
 
   history::DeleteDirectiveHandler delete_directive_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_SERVICE_H_