[chromecast] ExternalMetrics has to destroy itself in file thread.

chromecast/browser/metrics/cast_metrics_service_client.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 "chromecast/browser/metrics/cast_metrics_service_client.h"
 
 #include "base/command_line.h"
 #include "base/guid.h"
 #include "base/i18n/rtl.h"
 #include "base/prefs/pref_service.h"
@@ skipping 232 matching lines @@
   external_metrics_.reset(new ExternalMetrics(stability_provider));
   external_metrics_->Start();
 #endif  // defined(OS_LINUX)
 }
 
 void CastMetricsServiceClient::Finalize() {
 #if !defined(OS_ANDROID)
   // Set clean_shutdown bit.
   metrics_service_->RecordCompletedSessionEnd();
 #endif  // !defined(OS_ANDROID)
+
+  // Stop metrics service cleanly before destructing CastMetricsServiceClient.
+#if defined(OS_LINUX)
+  external_metrics_.release()->DestroySelf();
+#endif  // defined(OS_LINUX)
+  metrics_service_->Stop();
 }
 
 bool CastMetricsServiceClient::IsReportingEnabled() {
   return PlatformIsReportingEnabled(cast_service_);
 }
 
 }  // namespace metrics
 }  // namespace chromecast