Suppress sequence checks in SyncFileSystem on the shutdown phase

chrome/browser/sync_file_system/drive_backend/sync_task_manager.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/sync_task_manager.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/sequenced_task_runner.h"
@@ skipping 37 matching lines @@
     const PendingTask& left,
     const PendingTask& right) const {
   if (left.priority != right.priority)
     return left.priority < right.priority;
   return left.seq > right.seq;
 }
 
 SyncTaskManager::SyncTaskManager(
     base::WeakPtr<Client> client,
     size_t maximum_background_task,
-    const scoped_refptr<base::SequencedTaskRunner>& task_runner)
+    const scoped_refptr<base::SequencedTaskRunner>& task_runner,
+    const scoped_refptr<base::SequencedWorkerPool>& worker_pool)
     : client_(client),
       maximum_background_task_(maximum_background_task),
       pending_task_seq_(0),
       task_token_seq_(SyncTaskToken::kMinimumBackgroundTaskTokenID),
       task_runner_(task_runner),
+      worker_pool_(worker_pool),
       weak_ptr_factory_(this) {
 }
 
 SyncTaskManager::~SyncTaskManager() {
   weak_ptr_factory_.InvalidateWeakPtrs();
 
   client_.reset();
   token_.reset();
 }
 
@@ skipping 123 matching lines @@
   if (token_id == SyncTaskToken::kForegroundTaskTokenID)
     return true;
 
   return ContainsKey(running_background_tasks_, token_id);
 }
 
 void SyncTaskManager::DetachFromSequence() {
   sequence_checker_.DetachFromSequence();
 }
 
+bool SyncTaskManager::ShouldTrackTaskToken() const {
+  return !worker_pool_ || !worker_pool_->IsShutdownInProgress();
+}
+
 void SyncTaskManager::NotifyTaskDoneBody(scoped_ptr<SyncTaskToken> token,
                                          SyncStatusCode status) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   DCHECK(token);
 
   DVLOG(3) << "NotifyTaskDone: " << "finished with status=" << status
            << " (" << SyncStatusCodeToString(status) << ")"
            << " " << token->location().ToString();
 
   if (token->task_blocker()) {
@@ skipping 182 matching lines @@
     closure.Run();
     return;
   }
 
   if (client_)
     client_->MaybeScheduleNextTask();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system