Move some misc thread-related stuff from base to base/thread and into the bas...

base/worker_pool.h

-// Copyright (c) 2006-2008 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.
-
-#ifndef BASE_WORKER_POOL_H_
-#define BASE_WORKER_POOL_H_
-#pragma once
-
-#include "base/tracked.h"
-
-class Task;
-
-// This is a facility that runs tasks that don't require a specific thread or
-// a message loop.
-//
-// WARNING: This shouldn't be used unless absolutely necessary. We don't wait
-// for the worker pool threads to finish on shutdown, so the tasks running
-// inside the pool must be extremely careful about other objects they access
-// (MessageLoops, Singletons, etc). During shutdown these object may no longer
-// exist.
-class WorkerPool {
- public:
-  // This function posts |task| to run on a worker thread.  |task_is_slow|
-  // should be used for tasks that will take a long time to execute.  Returns
-  // false if |task| could not be posted to a worker thread.  Regardless of
-  // return value, ownership of |task| is transferred to the worker pool.
-  static bool PostTask(const tracked_objects::Location& from_here,
-                       Task* task, bool task_is_slow);
-};
-
-#endif  // BASE_WORKER_POOL_H_