[SyncFS] Run V2 backend tasks as SyncTask

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 "chrome/browser/sync_file_system/drive_backend/sync_task_manager.h"
 #include "chrome/browser/sync_file_system/drive_backend/task_dependency_manager.h"
 
@@ skipping 76 matching lines @@
 
 const BlockingFactor* SyncTaskToken::blocking_factor() const {
   return blocking_factor_.get();
 }
 
 void SyncTaskToken::clear_blocking_factor() {
   blocking_factor_.reset();
 }
 
 void SyncTaskToken::InitializeTaskLog(const std::string& task_description) {
-  DCHECK(task_log_);
   task_log_.reset(new TaskLogger::TaskLog);
   task_log_->start_time = base::TimeTicks::Now();
   task_log_->task_description = task_description;
 }
 
 void SyncTaskToken::FinalizeTaskLog(const std::string& result_description) {
   DCHECK(task_log_);
   task_log_->result_description = result_description;
   task_log_->end_time = base::TimeTicks::Now();
 }
@@ skipping 16 matching lines @@
                              scoped_ptr<BlockingFactor> blocking_factor,
                              const SyncStatusCallback& callback)
     : manager_(manager),
       token_id_(token_id),
       callback_(callback),
       blocking_factor_(blocking_factor.Pass()) {
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system