[reland] Use TaskScheduler instead of blocking pool in file_downloader.cc.

chrome/browser/net/file_downloader.cc

 // Copyright 2015 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/net/file_downloader.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/load_flags.h"
 #include "net/http/http_status_code.h"
 #include "net/url_request/url_fetcher.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 using net::URLFetcher;
 
 const int kNumRetries = 1;
@@ skipping 14 matching lines @@
   fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
                          net::LOAD_DO_NOT_SAVE_COOKIES);
   fetcher_->SetAutomaticallyRetryOnNetworkChanges(kNumRetries);
   fetcher_->SaveResponseToTemporaryFile(
       BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE));
 
   if (overwrite) {
     fetcher_->Start();
   } else {
     base::PostTaskAndReplyWithResult(
-        BrowserThread::GetBlockingPool()
-            ->GetTaskRunnerWithShutdownBehavior(
-                base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN)
+        base::CreateTaskRunnerWithTraits(
+            base::TaskTraits()
+                .MayBlock()
+                .WithPriority(base::TaskPriority::BACKGROUND)
+                .WithShutdownBehavior(
+                    base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN))
             .get(),
         FROM_HERE, base::Bind(&base::PathExists, local_path_),
         base::Bind(&FileDownloader::OnFileExistsCheckDone,
                    weak_ptr_factory_.GetWeakPtr()));
   }
 }
 
 FileDownloader::~FileDownloader() {}
 
 void FileDownloader::OnURLFetchComplete(const net::URLFetcher* source) {
@@ skipping 16 matching lines @@
   }
 
   base::FilePath response_path;
   bool success = source->GetResponseAsFilePath(false, &response_path);
   if (!success) {
     callback_.Run(FAILED);
     return;
   }
 
   base::PostTaskAndReplyWithResult(
-      BrowserThread::GetBlockingPool()
-          ->GetTaskRunnerWithShutdownBehavior(
-              base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN)
+      base::CreateTaskRunnerWithTraits(
+          base::TaskTraits()
+              .MayBlock()
+              .WithPriority(base::TaskPriority::BACKGROUND)
+              .WithShutdownBehavior(
+                  base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN))
           .get(),
       FROM_HERE, base::Bind(&base::Move, response_path, local_path_),
       base::Bind(&FileDownloader::OnFileMoveDone,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void FileDownloader::OnFileExistsCheckDone(bool exists) {
   if (exists)
     callback_.Run(EXISTS);
   else
     fetcher_->Start();
 }
 
 void FileDownloader::OnFileMoveDone(bool success) {
   if (!success) {
     DLOG(WARNING) << "Could not move file to "
                   << local_path_.LossyDisplayName();
   }
 
   callback_.Run(success ? DOWNLOADED : FAILED);
 }