Clear client id prefs when opting out of UMA.

chrome/installer/util/google_update_settings.cc

Index: chrome/installer/util/google_update_settings.cc
diff --git a/chrome/installer/util/google_update_settings.cc b/chrome/installer/util/google_update_settings.cc
index 5f68f938ae734dae3d690d599bec4e51177b441e..519c433244e33185eeedf001a562455e80956cd5 100644
--- a/chrome/installer/util/google_update_settings.cc
+++ b/chrome/installer/util/google_update_settings.cc
@@ -329,6 +329,11 @@ bool GoogleUpdateSettings::SetCollectStatsConsentAtLevel(bool system_install,
         << google_update::kRegUsageStatsField << " in key " << reg_path
         << "; result: " << result;
   }
+
+  // When opting out, clear registry backup of client id and related values.
+  if (result == ERROR_SUCCESS && !consented)
+    StoreMetricsClientInfo(metrics::ClientInfo());
+
   return (result == ERROR_SUCCESS);
 }