Suppress sequence checks in SyncFileSystem on the shutdown phase

chrome/browser/sync_file_system/drive_backend/sync_task_token.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_token.h"
 
 #include "base/bind.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "chrome/browser/sync_file_system/drive_backend/sync_task_manager.h"
@@ skipping 52 matching lines @@
 }
 
 SyncTaskToken::~SyncTaskToken() {
   // All task on Client must hold TaskToken instance to ensure
   // no other tasks are running. Also, as soon as a task finishes to work,
   // it must return the token to TaskManager.
   // Destroying a token with valid |client| indicates the token was
   // dropped by a task without returning.
   if (task_runner_.get() && task_runner_->RunsTasksOnCurrentThread() &&
       manager_ && manager_->IsRunningTask(token_id_)) {
+    if (!manager_->ShouldTrackTaskToken())
+      return;
+
     NOTREACHED()
         << "Unexpected TaskToken deletion from: " << location_.ToString();
 
     // Reinitializes the token.
     SyncTaskManager::NotifyTaskDone(
         make_scoped_ptr(new SyncTaskToken(manager_,
                                           task_runner_.get(),
                                           token_id_,
                                           task_blocker_.Pass(),
                                           SyncStatusCallback())),
@@ skipping 63 matching lines @@
     const SyncStatusCallback& callback)
     : manager_(manager),
       task_runner_(task_runner),
       token_id_(token_id),
       callback_(callback),
       task_blocker_(task_blocker.Pass()) {
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system