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

chromecast/browser/metrics/platform_metrics_providers_simple.cc

Index: chromecast/browser/metrics/platform_metrics_providers_simple.cc
diff --git a/chromecast/browser/metrics/platform_metrics_providers_simple.cc b/chromecast/browser/metrics/platform_metrics_providers_simple.cc
index c51caa382c9f68fed3df50e30892c751dc1ff53b..699289870ae3704b6af71d683c6173342f243a29 100644
--- a/chromecast/browser/metrics/platform_metrics_providers_simple.cc
+++ b/chromecast/browser/metrics/platform_metrics_providers_simple.cc
@@ -12,18 +12,5 @@ void RegisterPlatformMetricsProviders(
     CastService* cast_servce) {
 }
 
-const std::string GetPlatformClientID(CastService* cast_servce) {
-  return "";
-}
-
-::metrics::SystemProfileProto::Channel GetPlatformReleaseChannel(
-     CastService* cast_servce) {
-  return ::metrics::SystemProfileProto::CHANNEL_STABLE;
-}
-
-void PlatformSetClientID(CastService* cast_servce,
-                         const std::string& client_id) {
-}
-
 }  // namespace metrics
 }  // namespace chromecast