[TaskScheduler] Support TaskRunnerHandles from parallel tasks.

base/task_scheduler/task_tracker.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/task_scheduler/task_tracker.h"
 
 #include "base/callback.h"
 #include "base/debug/task_annotator.h"
 #include "base/metrics/histogram_macros.h"
-#include "base/threading/sequenced_task_runner_handle.h"
+#include "base/threading/task_runner_handle.h"
 #include "base/threading/thread_restrictions.h"
-#include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 
 namespace base {
 namespace internal {
 
 namespace {
 
 const char kQueueFunctionName[] = "base::PostTask";
 
 // This name conveys that a Task is run by the task scheduler without revealing
@@ skipping 65 matching lines @@
 
   // All tasks run through here and the scheduler itself doesn't use singletons.
   // Therefore, it isn't necessary to reset the singleton allowed bit after
   // running the task.
   ThreadRestrictions::SetSingletonAllowed(
       task->traits.shutdown_behavior() !=
       TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN);
 
   {
     // Set up TaskRunnerHandle as expected for the scope of the task.
-    std::unique_ptr<SequencedTaskRunnerHandle> sequenced_task_runner_handle;
-    std::unique_ptr<ThreadTaskRunnerHandle> single_thread_task_runner_handle;
-    DCHECK(!task->sequenced_task_runner_ref ||
-           !task->single_thread_task_runner_ref);
-    if (task->sequenced_task_runner_ref) {
-      sequenced_task_runner_handle.reset(
-          new SequencedTaskRunnerHandle(task->sequenced_task_runner_ref));
-    } else if (task->single_thread_task_runner_ref) {
-      single_thread_task_runner_handle.reset(
-          new ThreadTaskRunnerHandle(task->single_thread_task_runner_ref));
+    std::unique_ptr<TaskRunnerHandle::TaskScope> task_scope;
+    std::unique_ptr<TaskRunnerHandle::SequencedTaskScope> sequenced_task_scope;
+    std::unique_ptr<TaskRunnerHandle::SingleThreadTaskScope>
+        single_thread_task_scope;
+    if (task->task_runner_ref) {
+      DCHECK(!task->sequenced_task_runner_ref &&
+             !task->single_thread_task_runner_ref);
+      task_scope.reset(new TaskRunnerHandle::TaskScope(task->task_runner_ref));
+    } else if (task->sequenced_task_runner_ref) {
+      DCHECK(!task->single_thread_task_runner_ref);
+      sequenced_task_scope.reset(new TaskRunnerHandle::SequencedTaskScope(
+          task->sequenced_task_runner_ref));
+    } else {
+      DCHECK(task->single_thread_task_runner_ref);
+      single_thread_task_scope.reset(
+          new TaskRunnerHandle::SingleThreadTaskScope(
+              task->single_thread_task_runner_ref));
     }
 
     TRACE_TASK_EXECUTION(kRunFunctionName, *task);
 
     debug::TaskAnnotator task_annotator;
     task_annotator.RunTask(kQueueFunctionName, *task);
   }
 
   AfterRunTask(shutdown_behavior);
 }
@@ skipping 85 matching lines @@
     AutoSchedulerLock auto_lock(lock_);
     DCHECK_GT(num_tasks_blocking_shutdown_, 0U);
     --num_tasks_blocking_shutdown_;
     if (num_tasks_blocking_shutdown_ == 0 && shutdown_cv_)
       shutdown_cv_->Signal();
   }
 }
 
 }  // namespace internal
 }  // namespace base