Clear client id prefs when opting out of UMA.

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 cf1b4a126abd6af56515dfd07f84d84c1fbf01bf..e6d6c0713166b3e85694907c85a9bfabc9dbddcf 100644
--- a/components/metrics/metrics_state_manager.cc
+++ b/components/metrics/metrics_state_manager.cc
@@ -83,9 +83,6 @@ bool MetricsStateManager::IsMetricsReportingEnabled() {
 }
 
 void MetricsStateManager::ForceClientIdCreation() {
-  if (!client_id_.empty())
-    return;
-
   client_id_ = local_state_->GetString(prefs::kMetricsClientID);
   if (!client_id_.empty()) {
     // It is technically sufficient to only save a backup of the client id when