Remove unnecessary comment in metrics code

components/metrics/metrics_state_manager.cc

Index: components/metrics/metrics_state_manager.cc
diff --git a/components/metrics/metrics_state_manager.cc b/components/metrics/metrics_state_manager.cc
index ae0754e8ea1134b9e8ddcacca676ccb0c7772394..4cae20d3ae7be6df2815d0367e2e16d5998d86ba 100644
--- a/components/metrics/metrics_state_manager.cc
+++ b/components/metrics/metrics_state_manager.cc
@@ -261,10 +261,8 @@ MetricsStateManager::LoadClientInfoAndMaybeMigrate() {
   }
 
   // The GUID retrieved (and possibly fixed above) should be valid unless
-  // retrieval failed.
-  // DCHECK(!client_info || base::IsValidGUID(client_info->client_id));
-  // Temporary hack for http://crbug.com/635255.
-  // TODO(asvitkine): address this the right way.
+  // retrieval failed. If not, return nullptr. This will result in a new GUID
+  // being generated by the calling function ForceClientIdCreation().
   if (client_info && !base::IsValidGUID(client_info->client_id))
     return nullptr;