Port HistoryService::ScheduleDBTask to CancelableTaskTracker

chrome/browser/history/history_service.cc

 // 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.
 
 // The history system runs on a background thread so that potentially slow
 // database operations don't delay the browser. This backend processing is
 // represented by HistoryBackend. The HistoryService's job is to dispatch to
 // that thread.
 //
 // Main thread                       History thread
@@ skipping 358 matching lines @@
   ScheduleAndForget(PRIORITY_UI, &HistoryBackend::DeleteMatchingURLsForKeyword,
                     keyword_id, term);
 }
 
 void HistoryService::URLsNoLongerBookmarked(const std::set<GURL>& urls) {
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::URLsNoLongerBookmarked,
                     urls);
 }
 
-void HistoryService::ScheduleDBTask(history::HistoryDBTask* task,
-                                    CancelableRequestConsumerBase* consumer) {
+void HistoryService::ScheduleDBTask(scoped_refptr<history::HistoryDBTask> task,
+                                    base::CancelableTaskTracker* tracker) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  history::HistoryDBTaskRequest* request = new history::HistoryDBTaskRequest(
-      base::Bind(&history::HistoryDBTask::DoneRunOnMainThread, task));
-  request->value = task;  // The value is the task to execute.
-  Schedule(PRIORITY_UI, &HistoryBackend::ProcessDBTask, consumer, request);
+  base::CancelableTaskTracker::IsCanceledCallback is_canceled;
+  tracker->NewTrackedTaskId(&is_canceled);
+  thread_->message_loop_proxy()->PostTask(
+      FROM_HERE,
+      base::Bind(&HistoryBackend::ProcessDBTask,
+                 history_backend_.get(),
+                 task,
+                 base::ThreadTaskRunnerHandle::Get(),

[blundell, 2014/06/26 09:55:39]

Could you explain this parameter?

[sdefresne, 2014/06/28 08:14:26]

Done.

+                 is_canceled));
 }
 
 void HistoryService::FlushForTest(const base::Closure& flushed) {
   thread_->message_loop_proxy()->PostTaskAndReply(
       FROM_HERE, base::Bind(&base::DoNothing), flushed);
 }
 
 void HistoryService::SetOnBackendDestroyTask(const base::Closure& task) {
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::SetOnBackendDestroyTask,
@@ skipping 791 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
   visit_database_observers_.RemoveObserver(observer);
 }
 
 void HistoryService::NotifyVisitDBObserversOnAddVisit(
     const history::BriefVisitInfo& info) {
   DCHECK(thread_checker_.CalledOnValidThread());
   FOR_EACH_OBSERVER(history::VisitDatabaseObserver, visit_database_observers_,
                     OnAddVisit(info));
 }