[scheduler] Implement time-based cpu throttling.

third_party/WebKit/Source/platform/scheduler/base/task_queue_manager.cc

 // 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.
 
 #include "platform/scheduler/base/task_queue_manager.h"
 
 #include <queue>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 215 matching lines @@
   if (!delegate_->IsNested() && task_time_observers_.might_have_observers())
     task_start_time = lazy_now.Now();
 
   UpdateWorkQueues(lazy_now);
 
   for (int i = 0; i < work_batch_size_; i++) {
     internal::WorkQueue* work_queue;
     if (!SelectWorkQueueToService(&work_queue))
       break;
 
+    // TaskQueueManager guarantees that task queue will not be deleted
+    // when we are in DoWork (but WorkQueue may be deleted).
+    internal::TaskQueueImpl* task_queue = work_queue->task_queue();
+
     switch (ProcessTaskFromWorkQueue(work_queue)) {
       case ProcessTaskResult::DEFERRED:
         // If a task was deferred, try again with another task.
         continue;
       case ProcessTaskResult::EXECUTED:
         break;
       case ProcessTaskResult::TASK_QUEUE_MANAGER_DELETED:
         return;  // The TaskQueueManager got deleted, we must bail out.
     }
 
     lazy_now = real_time_domain()->CreateLazyNow();
     if (!delegate_->IsNested() && task_start_time != base::TimeTicks()) {
       // Only report top level task durations.
       base::TimeTicks task_end_time = lazy_now.Now();
-      FOR_EACH_OBSERVER(TaskTimeObserver, task_time_observers_,
-                        ReportTaskTime(MonotonicTimeInSeconds(task_start_time),
-                                       MonotonicTimeInSeconds(task_end_time)));
+      FOR_EACH_OBSERVER(
+          TaskTimeObserver, task_time_observers_,
+          ReportTaskTime(task_queue, MonotonicTimeInSeconds(task_start_time),
+                         MonotonicTimeInSeconds(task_end_time)));
       task_start_time = task_end_time;
     }
 
     work_queue = nullptr;  // The queue may have been unregistered.
 
     UpdateWorkQueues(lazy_now);
 
     // Only run a single task per batch in nested run loops so that we can
     // properly exit the nested loop when someone calls RunLoop::Quit().
     if (delegate_->IsNested())
@@ skipping 197 matching lines @@
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK(!work_queue->Empty());
   if (observer_) {
     observer_->OnTriedToExecuteBlockedTask(*work_queue->task_queue(),
                                            *work_queue->GetFrontTask());
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink