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

chromecast/browser/metrics/cast_metrics_service_client.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_CAST_METRICS_SERVICE_CLIENT_H_
 #define CHROMECAST_BROWSER_METRICS_CAST_METRICS_SERVICE_CLIENT_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 72 matching lines @@
 
   scoped_ptr< ::metrics::ClientInfo> LoadClientInfo();
   void StoreClientInfo(const ::metrics::ClientInfo& client_info);
 
   base::TaskRunner* const io_task_runner_;
   PrefService* const pref_service_;
   CastService* cast_service_;
   std::string client_id_;
 
 #if defined(OS_LINUX)
-  scoped_ptr<ExternalMetrics> external_metrics_;
+  ExternalMetrics* external_metrics_;
 #endif  // defined(OS_LINUX)
   const scoped_refptr<base::MessageLoopProxy> metrics_service_loop_;
   scoped_ptr< ::metrics::MetricsStateManager> metrics_state_manager_;
   scoped_ptr< ::metrics::MetricsService> metrics_service_;
   net::URLRequestContextGetter* const request_context_;
 
   DISALLOW_COPY_AND_ASSIGN(CastMetricsServiceClient);
 };
 
 }  // namespace metrics
 }  // namespace chromecast
 
 #endif  // CHROMECAST_BROWSER_METRICS_CAST_METRICS_SERVICE_CLIENT_H_