Use TaskScheduler instead of blocking pool in native_message_process_host.cc.

chrome/browser/extensions/api/messaging/native_message_process_host.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.
 
 #include "chrome/browser/extensions/api/messaging/native_message_process_host.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/process/kill.h"
 #include "base/task_scheduler/post_task.h"
-#include "base/threading/sequenced_worker_pool.h"
 #include "build/build_config.h"
 #include "chrome/browser/extensions/api/messaging/native_messaging_host_manifest.h"
 #include "chrome/browser/extensions/api/messaging/native_process_launcher.h"
 #include "content/public/browser/browser_thread.h"
 #include "extensions/common/constants.h"
 #include "extensions/common/features/feature.h"
 #include "net/base/file_stream.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "url/gurl.h"
@@ skipping 112 matching lines @@
     case NativeProcessLauncher::RESULT_SUCCESS:
       break;
   }
 
   process_ = std::move(process);
 #if defined(OS_POSIX)
   // This object is not the owner of the file so it should not keep an fd.
   read_file_ = read_file.GetPlatformFile();
 #endif
 
-  scoped_refptr<base::TaskRunner> task_runner(
-      content::BrowserThread::GetBlockingPool()->
-          GetTaskRunnerWithShutdownBehavior(
-              base::SequencedWorkerPool::SKIP_ON_SHUTDOWN));
+  scoped_refptr<base::TaskRunner> task_runner(base::CreateTaskRunnerWithTraits(
+      base::TaskTraits()
+          .MayBlock()
+          .WithPriority(base::TaskPriority::BACKGROUND)

[Devlin, 2017/04/24 20:22:11]

This task can spawn a new process, which seems like it should be USER_VISIBLE.

[Sergey Ulanov, 2017/04/24 21:24:17]

Yes, this should be USER_VISIBLE. Depending on application that calls the API
user may notice when there is a delay.

[fdoray, 2017/04/27 13:06:39]

Done.

+          .WithShutdownBehavior(base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN)));
 
   read_stream_.reset(new net::FileStream(std::move(read_file), task_runner));
   write_stream_.reset(new net::FileStream(std::move(write_file), task_runner));
 
   WaitRead();
   DoWrite();
 }
 
 void NativeMessageProcessHost::OnMessage(const std::string& json) {
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ skipping 189 matching lines @@
 
   if (!closed_) {
     closed_ = true;
     read_stream_.reset();
     write_stream_.reset();
     client_->CloseChannel(error_message);
   }
 }
 
 }  // namespace extensions