Convert //chrome/browser/supervised_user from scoped_ptr to std::unique_ptr

chrome/browser/supervised_user/supervised_user_pref_store.cc

Index: chrome/browser/supervised_user/supervised_user_pref_store.cc
diff --git a/chrome/browser/supervised_user/supervised_user_pref_store.cc b/chrome/browser/supervised_user/supervised_user_pref_store.cc
index 58fd556d0754fc63972bfa4a329b41277b6f333b..c2c9c046dcd3f8940be61de42bac44c7d1755710 100644
--- a/chrome/browser/supervised_user/supervised_user_pref_store.cc
+++ b/chrome/browser/supervised_user/supervised_user_pref_store.cc
@@ -112,7 +112,7 @@ SupervisedUserPrefStore::~SupervisedUserPrefStore() {
 
 void SupervisedUserPrefStore::OnNewSettingsAvailable(
     const base::DictionaryValue* settings) {
-  scoped_ptr<PrefValueMap> old_prefs = std::move(prefs_);
+  std::unique_ptr<PrefValueMap> old_prefs = std::move(prefs_);
   prefs_.reset(new PrefValueMap);
   if (settings) {
     // Set hardcoded prefs and defaults.