[Reland] Dont post delayed DoWork for disabled queues.

third_party/WebKit/Source/platform/scheduler/base/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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_
 
 #include <map>
 
 #include "base/atomic_sequence_num.h"
@@ skipping 56 matching lines @@
   // Requests that a task to process work is posted on the main task runner.
   // These tasks are de-duplicated in two buckets: main-thread and all other
   // threads.  This distinction is done to reduce the overehead from locks, we
   // assume the main-thread path will be hot.
   void MaybeScheduleImmediateWork(const tracked_objects::Location& from_here);
 
   // Requests that a delayed task to process work is posted on the main task
   // runner. These delayed tasks are de-duplicated. Must be called on the thread
   // this class was created on.
   void MaybeScheduleDelayedWork(const tracked_objects::Location& from_here,
-                                base::TimeTicks now,
-                                base::TimeDelta delay);
+                                LazyNow* lazy_now,
+                                base::TimeTicks run_time);
+
+  // Cancels a delayed task to process work at |run_time|, previously requested
+  // with MaybeScheduleDelayedWork.
+  void CancelDelayedWork(base::TimeTicks run_time);

[Sami, 2017/01/27 12:36:25]

What if one time domain accidentally cancels the wakeup requested by another
one? Do we need some refcounting here?

[alex clarke (OOO till 29th), 2017/01/30 18:24:01]

As discussed offline I've added some code to track which time domain is
associated with the wakeup.

 
   // Set the number of tasks executed in a single invocation of the task queue
   // manager. Increasing the batch size can reduce the overhead of yielding
   // back to the main message loop -- at the cost of potentially delaying other
   // tasks posted to the main loop. The batch size is 1 by default.
   void SetWorkBatchSize(int work_batch_size);
 
   // These functions can only be called on the same thread that the task queue
   // manager executes its tasks on.
   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer);
@@ skipping 225 matching lines @@
   scoped_refptr<DeletionSentinel> deletion_sentinel_;
   base::WeakPtrFactory<TaskQueueManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueueManager);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_MANAGER_H_