scheduler: Remove task observer shenanigans

components/scheduler/child/task_queue_manager.h

 // Copyright 2014 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 CONTENT_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_
 #define CONTENT_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_
 
 #include "base/atomic_sequence_num.h"
 #include "base/debug/task_annotator.h"
 #include "base/macros.h"
@@ skipping 185 matching lines @@
   // this.
   bool UpdateWorkQueues(bool should_trigger_wakeup,
                         const base::PendingTask* previous_task);
 
   // Chooses the next work queue to service. Returns true if |out_queue_index|
   // indicates the queue from which the next task should be run, false to
   // avoid running any tasks.
   bool SelectWorkQueueToService(size_t* out_queue_index);
 
   // Runs a single nestable task from the work queue designated by
-  // |queue_index|. If |has_previous_task| is true, |previous_task| should
-  // contain the previous task in this work batch. Non-nestable task are
-  // reposted on the run loop. The queue must not be empty.
-  // Returns true if the TaskQueueManager got deleted, and false otherwise.
+  // |queue_index|. On exit, |out_task| will contain the task which was
+  // executed. Non-nestable task are reposted on the run loop. The queue must
+  // not be empty. Returns true if the TaskQueueManager got deleted, and false
+  // otherwise.
   bool ProcessTaskFromWorkQueue(size_t queue_index,
-                                bool has_previous_task,
-                                base::PendingTask* previous_task);
+                                base::PendingTask* out_task);
 
   bool RunsTasksOnCurrentThread() const;
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay);
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const base::Closure& task,
                                   base::TimeDelta delay);
   internal::TaskQueueImpl* Queue(size_t queue_index) const;
 
@@ skipping 33 matching lines @@
 
   scoped_refptr<DeletionSentinel> deletion_sentinel_;
   base::WeakPtrFactory<TaskQueueManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueueManager);
 };
 
 }  // namespace scheduler
 
 #endif  // CONTENT_RENDERER_SCHEDULER_TASK_QUEUE_MANAGER_H_