TaskScheduler: Add TaskRunnerHandle support to TaskScheduler tasks

base/task_scheduler/scheduler_thread_pool.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/scheduler_thread_pool.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 68 matching lines @@
                                DelayedTaskManager* delayed_task_manager)
       : traits_(traits),
         executor_(executor),
         task_tracker_(task_tracker),
         delayed_task_manager_(delayed_task_manager) {}
 
   // SequencedTaskRunner:
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const Closure& closure,
                        TimeDelta delay) override {
+    std::unique_ptr<Task> task(
+        new Task(from_here, closure, traits_,
+                 delay.is_zero() ? TimeTicks() : TimeTicks::Now() + delay));
+    task->sequenced_task_runner_ref = this;
+
     // Post the task as part of |sequence|.
-    return PostTaskToExecutor(
-        WrapUnique(
-            new Task(from_here, closure, traits_,
-                     delay.is_zero() ? TimeTicks() : TimeTicks::Now() + delay)),
-        sequence_, executor_, task_tracker_, delayed_task_manager_);
+    return PostTaskToExecutor(std::move(task), sequence_, executor_,
+                              task_tracker_, delayed_task_manager_);
   }
 
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const Closure& closure,
                                   base::TimeDelta delay) override {
     // Tasks are never nested within the task scheduler.
     return PostDelayedTask(from_here, closure, delay);
   }
 
   bool RunsTasksOnCurrentThread() const override {
@@ skipping 239 matching lines @@
   if (idle_worker_threads_stack_.empty())
     return nullptr;
 
   auto worker_thread = idle_worker_threads_stack_.top();
   idle_worker_threads_stack_.pop();
   return worker_thread;
 }
 
 }  // namespace internal
 }  // namespace base