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 0ab8bddaf5f1149c52008f1faa8608eda3984124..5c6f13bd068d638f8530603f82f3730556991085 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)
+    GoogleUpdateSettings::StoreMetricsClientInfo(metrics::ClientInfo());

[grt (UTC plus 2), 2016/08/12 19:43:32]

nit: omit "GoogleUpdateSettings::"

[Alexei Svitkine (slow), 2016/08/12 22:29:58]

Done.

+
   return (result == ERROR_SUCCESS);
 }