Move and rename TaskTimeTracker to public interface exposed to WebThread, use in WebPerf Agent.

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"
 #include "base/debug/task_annotator.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/pending_task.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "platform/scheduler/base/enqueue_order.h"
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/base/task_queue_selector.h"
+#include "public/platform/WebThread.h"
 
 namespace base {
 class TickClock;
 
 namespace trace_event {
 class ConvertableToTraceFormat;
 class TracedValue;
 }  // namespace trace_event
 }  // namespace base
 
 namespace blink {
 namespace scheduler {
 namespace internal {
 class TaskQueueImpl;
 }  // namespace internal
 
 class LazyNow;
 class RealTimeDomain;
 class TimeDomain;
 class TaskQueueManagerDelegate;
-class TaskTimeTracker;
 
 // The task queue manager provides N task queues and a selector interface for
 // choosing which task queue to service next. Each task queue consists of two
 // sub queues:
 //
 // 1. Incoming task queue. Tasks that are posted get immediately appended here.
 //    When a task is appended into an empty incoming queue, the task manager
 //    work function (DoWork) is scheduled to run on the main task runner.
 //
 // 2. Work queue. If a work queue is empty when DoWork() is entered, tasks from
@@ skipping 24 matching lines @@
   void MaybeScheduleDelayedWork(const tracked_objects::Location& from_here,
                                 base::TimeTicks now,
                                 base::TimeDelta delay);
 
   // 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);
 
-  // When given a non-null TaskTimeTracker, the TaskQueueManager calls its
-  // ReportTaskTime method for every top level task. The task_time_tracker must
-  // outlive this object, or be removed via SetTaskTimeTracker(nullptr).
-  void SetTaskTimeTracker(TaskTimeTracker* task_time_tracker) {
-    task_time_tracker_ = task_time_tracker;
-  }
-
   // 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);
   void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer);
+  void AddTaskTimeObserver(WebThread::TaskTimeObserver* task_time_observer);

[Sami, 2016/08/22 15:51:30]

Earlier I really should've talked about base/ vs. not-base since as you rightly
pointed out, WebThread is in platform/ too. Anyway, what I was trying to say was
that scheduler/base is used to implement WebThread, so it's a little odd for it
to depend on it too. How about instead we do this:

1. Add an abstract TaskTimeObserver class here (a separate header maybe).
2. Add a "using scheduler::TaskTimeObserver" in WebThread to bring it into scope
(or we could just use it directly there).

WDYT?

[panickercorp, 2016/08/22 16:55:45]

I agree it makes sense to make it a separate interface and decouple from
WebThread, given what you said.
However the question is whether it should live in:
third_party/WebKit/public/platform/  OR
third_party/WebKit/public/platform/scheduler/base/
The former seems like it would be more consistent with existing code structure
and deps than latter.
However I'll start with latter and see what folks think.

[Sami, 2016/08/22 17:02:58]

The latter sounds good to me. I think we're still figuring out how the scheduler
code will eventually meld into Blink.

[panicker, 2016/08/22 23:14:14]

Done.

+  void RemoveTaskTimeObserver(WebThread::TaskTimeObserver* task_time_observer);
 
   // Returns true if any task from a monitored task queue was was run since the
   // last call to GetAndClearSystemIsQuiescentBit.
   bool GetAndClearSystemIsQuiescentBit();
 
   // Creates a task queue with the given |spec|.  Must be called on the thread
   // this class was created on.
   scoped_refptr<internal::TaskQueueImpl> NewTaskQueue(
       const TaskQueue::Spec& spec);
 
@@ skipping 134 matching lines @@
 
   // Protects |other_thread_pending_wakeups_|.
   mutable base::Lock other_thread_lock_;
   std::set<base::TimeTicks> other_thread_pending_wakeups_;
 
   int work_batch_size_;
   size_t task_count_;
 
   base::ObserverList<base::MessageLoop::TaskObserver> task_observers_;
 
-  TaskTimeTracker* task_time_tracker_;  // NOT OWNED
+  bool has_task_time_observer;

[alph, 2016/08/22 22:21:27]

Is it used?

[panicker, 2016/08/22 23:14:14]

Removed in new patch

+  base::ObserverList<WebThread::TaskTimeObserver> task_time_observers_;
 
   const char* tracing_category_;
   const char* disabled_by_default_tracing_category_;
   const char* disabled_by_default_verbose_tracing_category_;
 
   internal::TaskQueueImpl* currently_executing_task_queue_;  // NOT OWNED
 
   Observer* observer_;  // NOT OWNED
   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_