[Reland] Dont post delayed DoWork for disabled queues.

third_party/WebKit/public/platform/scheduler/base/task_queue.h

 // Copyright 2015 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_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_H_
 #define THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_H_
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/optional.h"
@@ skipping 132 matching lines @@
   // Returns true if the queue is completely empty.
   virtual bool IsEmpty() const = 0;
 
   // Returns the number of pending tasks in the queue.
   virtual size_t GetNumberOfPendingTasks() const = 0;
 
   // Returns true if the queue has work that's ready to execute now.
   // NOTE: this must be called on the thread this TaskQueue was created by.
   virtual bool HasPendingImmediateWork() const = 0;
 
-  // Returns requested run time of next delayed task, which is not ready
-  // to run. If there are no such tasks, returns base::nullopt.
+  // Returns requested run time of next scheduled wakeup for a delayed task
+  // which is not ready to run. If there are no such tasks or the queue is
+  // disabled (by a QueueEnabledVoter) it returns base::nullopt.
   // NOTE: this must be called on the thread this TaskQueue was created by.
   virtual base::Optional<base::TimeTicks> GetNextScheduledWakeUp() = 0;
 
   // Can be called on any thread.
   virtual QueueType GetQueueType() const = 0;
 
   // Can be called on any thread.
   virtual const char* GetName() const = 0;
 
   // Set the priority of the queue to |priority|. NOTE this must be called on
@@ skipping 45 matching lines @@
  protected:
   ~TaskQueue() override {}
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueue);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_QUEUE_H_