Introduce TaskRunnerHandle.

base/threading/thread_task_runner_handle.cc

 // Copyright 2016 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 "base/threading/thread_task_runner_handle.h"
 
 #include <utility>
 
-#include "base/lazy_instance.h"
-#include "base/logging.h"
-#include "base/threading/sequenced_task_runner_handle.h"
-#include "base/threading/thread_local.h"
-
 namespace base {
 
-namespace {
-
-base::LazyInstance<base::ThreadLocalPointer<ThreadTaskRunnerHandle>>::Leaky
-    lazy_tls_ptr = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-// static
-scoped_refptr<SingleThreadTaskRunner> ThreadTaskRunnerHandle::Get() {
-  ThreadTaskRunnerHandle* current = lazy_tls_ptr.Pointer()->Get();
-  DCHECK(current);
-  return current->task_runner_;
-}
-
-// static
-bool ThreadTaskRunnerHandle::IsSet() {
-  return !!lazy_tls_ptr.Pointer()->Get();
-}
-
 ThreadTaskRunnerHandle::ThreadTaskRunnerHandle(
     scoped_refptr<SingleThreadTaskRunner> task_runner)
-    : task_runner_(std::move(task_runner)) {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  // No SequencedTaskRunnerHandle (which includes ThreadTaskRunnerHandles)
-  // should already be set for this thread.
-  DCHECK(!SequencedTaskRunnerHandle::IsSet());
-  lazy_tls_ptr.Pointer()->Set(this);
-}
+    : task_scope_(std::move(task_runner)) {}
 
-ThreadTaskRunnerHandle::~ThreadTaskRunnerHandle() {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK_EQ(lazy_tls_ptr.Pointer()->Get(), this);
-  lazy_tls_ptr.Pointer()->Set(nullptr);
-}
+ThreadTaskRunnerHandle::~ThreadTaskRunnerHandle() = default;
 
 }  // namespace base