Expected Queueing Time Metric ignores tasks with nested message loops.

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 170 matching lines @@
 }
 
 void TaskQueueManager::OnBeginNestedMessageLoop() {
   // We just entered a nested message loop, make sure there's a DoWork posted or
   // the system will grind to a halt.
   {
     base::AutoLock lock(any_thread_lock_);
     any_thread().immediate_do_work_posted_count++;
     any_thread().is_nested = true;
   }
+
+  // When a nested message loop starts, task time observers may want to ignore
+  // the current task.
+  for (auto& observer : task_time_observers_)
+    observer.onBeginNestedMessageLoop();
+
   delegate_->PostTask(FROM_HERE, immediate_do_work_closure_);
 }
 
 void TaskQueueManager::OnQueueHasIncomingImmediateWork(
     internal::TaskQueueImpl* queue,
     internal::EnqueueOrder enqueue_order,
     bool queue_is_blocked) {
   MoveableAutoLock lock(any_thread_lock_);
   any_thread().has_incoming_immediate_work.insert(
       std::make_pair(queue, enqueue_order));
@@ skipping 504 matching lines @@
   for (const scoped_refptr<internal::TaskQueueImpl>& queue : queues_) {
     TimeDomain* time_domain = queue->GetTimeDomain();
     if (time_domain_now.find(time_domain) == time_domain_now.end())
       time_domain_now.insert(std::make_pair(time_domain, time_domain->Now()));
     queue->SweepCanceledDelayedTasks(time_domain_now[time_domain]);
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink