Revert of [scheduler] Add TaskQueue::Observer

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 02be214e55591f00dd7fc00dd2c297678b504743..ec4e74e9a0bfe1587093cc87c25d1d7f3268751a 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
@@ -46,7 +46,7 @@ class WorkQueueSets;
 // immediate_work_queue is swapped with immediate_incoming_queue when
 // immediate_work_queue becomes empty.
 //
-// Delayed tasks are initially posted to delayed_incoming_queue and a wake-up
+// Delayed tasks are initially posted to delayed_incoming_queue and a wakeup
 // is scheduled with the TimeDomain.  When the delay has elapsed, the TimeDomain
 // calls UpdateDelayedWorkQueue and ready delayed tasks are moved into the
 // delayed_work_queue.  Note the EnqueueOrder (used for ordering) for a delayed
@@ -65,21 +65,6 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
                 const char* disabled_by_default_tracing_category,
                 const char* disabled_by_default_verbose_tracing_category);
 
-  // Represents a time at which a task wants to run. Tasks scheduled for the
-  // same point in time will be ordered by their sequence numbers.
-  struct DelayedWakeUp {
-    base::TimeTicks time;
-    int sequence_num;
-
-    bool operator<=(const DelayedWakeUp& other) const {
-      if (time == other.time) {
-        DCHECK_NE(sequence_num, other.sequence_num);
-        return (sequence_num - other.sequence_num) < 0;
-      }
-      return time < other.time;
-    }
-  };
-
   class BLINK_PLATFORM_EXPORT Task : public base::PendingTask {
    public:
     Task();
@@ -96,10 +81,6 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
          bool nestable,
          EnqueueOrder enqueue_order);
 
-    DelayedWakeUp delayed_wake_up() const {
-      return DelayedWakeUp{delayed_run_time, sequence_num};
-    }
-
     EnqueueOrder enqueue_order() const {
 #ifndef NDEBUG
       DCHECK(enqueue_order_set_);
@@ -131,6 +112,21 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     EnqueueOrder enqueue_order_;
   };
 
+  // Represents a time at which a task wants to run. Tasks scheduled for the
+  // same point in time will be ordered by their sequence numbers.
+  struct DelayedWakeUp {
+    base::TimeTicks time;
+    int sequence_num;
+
+    bool operator<=(const DelayedWakeUp& other) const {
+      if (time == other.time) {
+        DCHECK_NE(sequence_num, other.sequence_num);
+        return (sequence_num - other.sequence_num) < 0;
+      }
+      return time < other.time;
+    }
+  };
+
   // TaskQueue implementation.
   void UnregisterTaskQueue() override;
   bool RunsTasksOnCurrentThread() const override;
@@ -159,7 +155,6 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   bool BlockedByFence() const override;
   const char* GetName() const override;
   QueueType GetQueueType() const override;
-  void SetObserver(Observer* observer) override;
 
   // Returns true if a (potentially hypothetical) task with the specified
   // |enqueue_order| could run on the queue. Must be called from the main
@@ -198,18 +193,18 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   }
 
   // Enqueues any delayed tasks which should be run now on the
-  // |delayed_work_queue|. Returns the subsequent wake-up that is required, if
+  // |delayed_work_queue|. Returns the subsequent wakeup that is required, if
   // any. Must be called from the main thread.
   base::Optional<DelayedWakeUp> WakeUpForDelayedWork(LazyNow* lazy_now);
 
-  base::TimeTicks scheduled_time_domain_wake_up() const {
-    return main_thread_only().scheduled_time_domain_wake_up;
+  base::TimeTicks scheduled_time_domain_wakeup() const {
+    return main_thread_only().scheduled_time_domain_wakeup;
   }
 
-  void set_scheduled_time_domain_wake_up(
-      base::TimeTicks scheduled_time_domain_wake_up) {
-    main_thread_only().scheduled_time_domain_wake_up =
-        scheduled_time_domain_wake_up;
+  void set_scheduled_time_domain_wakeup(
+      base::TimeTicks scheduled_time_domain_wakeup) {
+    main_thread_only().scheduled_time_domain_wakeup =
+        scheduled_time_domain_wakeup;
   }
 
   HeapHandle heap_handle() const { return main_thread_only().heap_handle; }
@@ -254,12 +249,11 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     AnyThread(TaskQueueManager* task_queue_manager, TimeDomain* time_domain);
     ~AnyThread();
 
-    // TaskQueueManager, TimeDomain and Observer are maintained in two copies:
+    // TaskQueueManager and TimeDomain are maintained in two copies:
     // inside AnyThread and inside MainThreadOnly. They can be changed only from
     // main thread, so it should be locked before accessing from other threads.
     TaskQueueManager* task_queue_manager;
     TimeDomain* time_domain;
-    Observer* observer;
   };
 
   struct MainThreadOnly {
@@ -268,12 +262,10 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
                    TimeDomain* time_domain);
     ~MainThreadOnly();
 
-    // Another copy of TaskQueueManager, TimeDomain and Observer
-    // for lock-free access from the main thread.
-    // See description inside struct AnyThread for details.
+    // Another copy of TaskQueueManager and TimeDomain for lock-free access from
+    // the main thread. See description inside struct AnyThread for details.
     TaskQueueManager* task_queue_manager;
     TimeDomain* time_domain;
-    Observer* observer;
 
     std::unique_ptr<WorkQueue> delayed_work_queue;
     std::unique_ptr<WorkQueue> immediate_work_queue;
@@ -285,7 +277,7 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     int voter_refcount;
     base::trace_event::BlameContext* blame_context;  // Not owned.
     EnqueueOrder current_fence;
-    base::TimeTicks scheduled_time_domain_wake_up;
+    base::TimeTicks scheduled_time_domain_wakeup;
   };
 
   ~TaskQueueImpl() override;
@@ -337,11 +329,6 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   void OnQueueEnabledVoteChanged(bool enabled);
   void EnableOrDisableWithSelector(bool enable);
 
-  // Schedules delayed work on time domain and calls the observer.
-  void ScheduleDelayedWorkInTimeDomain(base::TimeTicks now);
-
-  void NotifyWakeUpChangedOnMainThread(base::TimeTicks wake_up);
-
   const base::PlatformThreadId thread_id_;
 
   mutable base::Lock any_thread_lock_;