Add missing #include around sequenced_worker_pool.h

chromecast/browser/metrics/external_metrics.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 CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_
 #define CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_
 
 #include <string>
 
+#include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/sequenced_task_runner_helpers.h"
 
 namespace metrics {
 class MetricSample;
 }  // namespace metrics
 
 namespace chromecast {
 namespace metrics {
 
 class CastStabilityMetricsProvider;
 
@@ skipping 46 matching lines @@
 
   base::WeakPtrFactory<ExternalMetrics> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalMetrics);
 };
 
 }  // namespace metrics
 }  // namespace chromecast
 
 #endif  // CHROMECAST_BROWSER_METRICS_EXTERNAL_METRICS_H_