Add the concept of QueueEnabledVoters to blink scheduler TaskQueue

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
index d4db9b663066386143aba5c31dd3b592a25e567f..4ace7a39f4b1674c182396245df2e8a3d2576b86 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
@@ -119,7 +119,7 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
                                   const base::Closure& task,
                                   base::TimeDelta delay) override;
-  void SetQueueEnabled(bool enabled) override;
+  std::unique_ptr<QueueEnabledVoter> GetQueueEnabledVoter() override;

[Sami, 2016/11/29 14:45:17]

s/Get/Create/ to make this a bit more obvious.

[alex clarke (OOO till 29th), 2016/11/29 16:49:11]

Done.

   bool IsQueueEnabled() const override;
   bool IsEmpty() const override;
   size_t GetNumberOfPendingTasks() const override;
@@ -136,14 +136,13 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   void InsertFence(InsertFencePosition position) override;
   void RemoveFence() override;
   bool BlockedByFence() const override;
+  const char* GetName() const override;
+  QueueType GetQueueType() const override;
 
   // If this returns false then future updates for this queue are not needed
   // unless requested.
   bool MaybeUpdateImmediateWorkQueues();
 
-  const char* GetName() const override;
-  QueueType GetQueueType() const override;
-
   void AsValueInto(base::trace_event::TracedValue* state) const;
 
   bool GetQuiescenceMonitored() const { return should_monitor_quiescence_; }
@@ -234,12 +233,29 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     base::ObserverList<base::MessageLoop::TaskObserver> task_observers;
     size_t set_index;
     HeapHandle heap_handle;
-    bool is_enabled;
+    int is_enabled_refcount;
+    int voter_refcount;
     base::trace_event::BlameContext* blame_context;  // Not owned.
     EnqueueOrder current_fence;
     base::TimeTicks scheduled_time_domain_wakeup;
   };
 
+  class QueueEnabledVoterImpl : public QueueEnabledVoter {
+   public:
+    explicit QueueEnabledVoterImpl(TaskQueueImpl* task_queue);
+    ~QueueEnabledVoterImpl() override;
+
+    // QueueEnabledVoter implementation.
+    void SetQueueEnabled(bool enabled) override;
+    TaskQueue* GetTaskQueue() const override;
+
+   private:
+    friend class TaskQueueImpl;
+
+    scoped_refptr<TaskQueueImpl> task_queue_;
+    bool enabled_;
+  };
+
   ~TaskQueueImpl() override;
 
   bool PostImmediateTaskImpl(const tracked_objects::Location& from_here,
@@ -284,6 +300,10 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   static void TaskAsValueInto(const Task& task,
                               base::trace_event::TracedValue* state);
 
+  void RemoveQueueEnabledVoter(const QueueEnabledVoterImpl* voter);
+  void QueueEnabledVoteChanged(bool enabled);

[Sami, 2016/11/29 14:45:16]

nit: OnQueueEnabledVoteChanged?

[alex clarke (OOO till 29th), 2016/11/29 16:49:11]

Done.

+  void EnableOrDisableWithSelector(bool enable);
+
   const base::PlatformThreadId thread_id_;
 
   mutable base::Lock any_thread_lock_;