Add an api to disable recording task delay histogrames

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 125 matching lines @@
 
   // Return number of pending tasks in task queues.
   size_t GetNumberOfPendingTasks() const;
 
   // Returns true if there is a task that could be executed immediately.
   bool HasImmediateWorkForTesting() const;
 
   // Removes all canceled delayed tasks.
   void SweepCanceledDelayedTasks();
 
+  // There is a small overhead to recording task delay histograms. If you don't
+  // need them, you can turn them off.
+  void SetRecordTaskDelayHistograms(bool record_task_delay_histograms);
+
  private:
   friend class LazyNow;
   friend class internal::TaskQueueImpl;
   friend class TaskQueueManagerTest;
 
   class DeletionSentinel : public base::RefCounted<DeletionSentinel> {
    private:
     friend class base::RefCounted<DeletionSentinel>;
     ~DeletionSentinel() {}
   };
@@ skipping 83 matching lines @@
   bool task_was_run_on_quiescence_monitored_queue_;
 
   // To reduce locking overhead we track pending calls to DoWork separately for
   // the main thread and other threads.
   std::set<base::TimeTicks> main_thread_pending_wakeups_;
 
   // Protects |other_thread_pending_wakeup_|.
   mutable base::Lock other_thread_lock_;
   bool other_thread_pending_wakeup_;
 
+  bool record_task_delay_histograms_;
+
   int work_batch_size_;
   size_t task_count_;
 
   base::ObserverList<base::MessageLoop::TaskObserver> task_observers_;
 
   base::ObserverList<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_