Change more base::ListValue methods to use std::unique_ptr.

chrome/browser/chromeos/policy/affiliation_test_helper.cc

Index: chrome/browser/chromeos/policy/affiliation_test_helper.cc
diff --git a/chrome/browser/chromeos/policy/affiliation_test_helper.cc b/chrome/browser/chromeos/policy/affiliation_test_helper.cc
index 8cdfc1f511a969b559bb650556b6b9cd303424de..8ef2dcef098ea43481a39ede76be4c21eb12dd5e 100644
--- a/chrome/browser/chromeos/policy/affiliation_test_helper.cc
+++ b/chrome/browser/chromeos/policy/affiliation_test_helper.cc
@@ -10,6 +10,7 @@
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
+#include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ -99,7 +100,7 @@ void SetUserAffiliationIDs(
 
 void PreLoginUser(const std::string& user_id) {
   ListPrefUpdate users_pref(g_browser_process->local_state(), "LoggedInUsers");
-  users_pref->AppendIfNotPresent(new base::StringValue(user_id));
+  users_pref->AppendIfNotPresent(base::MakeUnique<base::StringValue>(user_id));
   chromeos::StartupUtils::MarkOobeCompleted();
 }