DCHECK tasks posted by TaskRunner::PostTask

base/deferred_sequenced_task_runner.cc

 // Copyright (c) 2013 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/deferred_sequenced_task_runner.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 54 matching lines @@
   QueueDeferredTask(from_here, std::move(task), delay,
                     true /* is_non_nestable */);
   return true;
 }
 
 void DeferredSequencedTaskRunner::QueueDeferredTask(
     const tracked_objects::Location& from_here,
     Closure task,
     TimeDelta delay,
     bool is_non_nestable) {
+  DCHECK(task);
+
   DeferredTask deferred_task;
   deferred_task.posted_from = from_here;
   deferred_task.task = std::move(task);
   deferred_task.delay = delay;
   deferred_task.is_non_nestable = is_non_nestable;
   deferred_tasks_queue_.push_back(std::move(deferred_task));
 }
 
 void DeferredSequencedTaskRunner::Start() {
   AutoLock lock(lock_);
   DCHECK(!started_);
   started_ = true;
   for (std::vector<DeferredTask>::iterator i = deferred_tasks_queue_.begin();
       i != deferred_tasks_queue_.end();
       ++i) {
     DeferredTask& task = *i;
     if (task.is_non_nestable) {
       target_task_runner_->PostNonNestableDelayedTask(
           task.posted_from, std::move(task.task), task.delay);
     } else {
       target_task_runner_->PostDelayedTask(task.posted_from,
                                            std::move(task.task), task.delay);
     }
   }
   deferred_tasks_queue_.clear();
 }
 
 }  // namespace base