Remove adapter method on HistoryBackend delegating to AndroidProviderBackend

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 333 matching lines @@
 void HistoryService::AddObserver(history::HistoryServiceObserver* observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
   observers_.AddObserver(observer);
 }
 
 void HistoryService::RemoveObserver(history::HistoryServiceObserver* observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
   observers_.RemoveObserver(observer);
 }
 
-void HistoryService::ScheduleDBTask(scoped_ptr<history::HistoryDBTask> task,
-                                    base::CancelableTaskTracker* tracker) {
+base::CancelableTaskTracker::TaskId HistoryService::ScheduleDBTask(
+    scoped_ptr<history::HistoryDBTask> task,
+    base::CancelableTaskTracker* tracker) {
   DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   base::CancelableTaskTracker::IsCanceledCallback is_canceled;
-  tracker->NewTrackedTaskId(&is_canceled);
+  base::CancelableTaskTracker::TaskId task_id =
+      tracker->NewTrackedTaskId(&is_canceled);
   // Use base::ThreadTaskRunnerHandler::Get() to get a message loop proxy to
   // the current message loop so that we can forward the call to the method
-  // HistoryDBTask::DoneRunOnMainThread in the correct thread.
+  // HistoryDBTask::DoneRunOnMainThread() in the correct thread.
   thread_->message_loop_proxy()->PostTask(
       FROM_HERE,
       base::Bind(&HistoryBackend::ProcessDBTask,
                  history_backend_.get(),
                  base::Passed(&task),
                  base::ThreadTaskRunnerHandle::Get(),
                  is_canceled));
+  return task_id;
 }
 
 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_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
@@ skipping 895 matching lines @@
     const HistoryService::OnFaviconChangedCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   return favicon_changed_callback_list_.Add(callback);
 }
 
 void HistoryService::NotifyFaviconChanged(
     const std::set<GURL>& changed_favicons) {
   DCHECK(thread_checker_.CalledOnValidThread());
   favicon_changed_callback_list_.Notify(changed_favicons);
 }