Reland of move header dependencies from sequence_checker.h to sequenced_worker_pool.h

chrome/browser/chromeos/external_metrics.cc

 // Copyright (c) 2012 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 "chrome/browser/chromeos/external_metrics.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <string>
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/metrics/statistics_recorder.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/metrics/chromeos_metrics_provider.h"
 #include "components/metrics/metrics_service.h"
 #include "components/metrics/serialization/metric_sample.h"
 #include "components/metrics/serialization/serialization_utils.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/user_metrics.h"
 
 using base::UserMetricsAction;
 using content::BrowserThread;
@@ skipping 146 matching lines @@
 
 void ExternalMetrics::ScheduleCollector() {
   bool result = BrowserThread::GetBlockingPool()->PostDelayedWorkerTask(
       FROM_HERE,
       base::Bind(&chromeos::ExternalMetrics::CollectEventsAndReschedule, this),
       base::TimeDelta::FromSeconds(kExternalMetricsCollectionIntervalSeconds));
   DCHECK(result);
 }
 
 }  // namespace chromeos