[Chromecast] Moves persistent UMA client ID handling to common code.

chromecast/browser/metrics/cast_metrics_service_client.h

Index: chromecast/browser/metrics/cast_metrics_service_client.h
diff --git a/chromecast/browser/metrics/cast_metrics_service_client.h b/chromecast/browser/metrics/cast_metrics_service_client.h
index 771b78edb02f0342c74472705700cd83755190b5..f196c10b1359b1c8b6696b058c7078d39fa5bd31 100644
--- a/chromecast/browser/metrics/cast_metrics_service_client.h
+++ b/chromecast/browser/metrics/cast_metrics_service_client.h
@@ -48,6 +48,10 @@ class CastMetricsServiceClient : public ::metrics::MetricsServiceClient {
       net::URLRequestContextGetter* request_context);
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
+  // Use |client_id| when starting MetricsService instead of generating a new
+  // client ID. Must be called before Initialize.

[byungchul, 2015/08/19 21:38:19]

comment that it is optional.

[gunsch, 2015/08/19 21:46:51]

Done.

+  void SetForceClientId(const std::string& client_id);
+
   void Initialize(CastService* cast_service);
   void Finalize();
 
@@ -87,6 +91,8 @@ class CastMetricsServiceClient : public ::metrics::MetricsServiceClient {
   PrefService* const pref_service_;
   CastService* cast_service_;
   std::string client_id_;
+  std::string force_client_id_;
+  bool client_info_loaded_;
 
 #if defined(OS_LINUX)
   ExternalMetrics* external_metrics_;