Use std::unique_ptr for base::DictionaryValue and base::ListValue's internal store.

chrome/browser/spellchecker/spellcheck_service.cc

Index: chrome/browser/spellchecker/spellcheck_service.cc
diff --git a/chrome/browser/spellchecker/spellcheck_service.cc b/chrome/browser/spellchecker/spellcheck_service.cc
index 180823d8d90bd25f7740319e659be315ef5c8c19..a7ba7ce6c8079f29f0d1cfd198d51b9785743d01 100644
--- a/chrome/browser/spellchecker/spellcheck_service.cc
+++ b/chrome/browser/spellchecker/spellcheck_service.cc
@@ -225,7 +225,7 @@ void SpellcheckService::LoadHunspellDictionaries() {
   const base::ListValue* dictionary_values =
       prefs->GetList(prefs::kSpellCheckDictionaries);
 
-  for (const base::Value* dictionary_value : *dictionary_values) {
+  for (const auto& dictionary_value : *dictionary_values) {
     std::string dictionary;
     dictionary_value->GetAsString(&dictionary);
     hunspell_dictionaries_.push_back(new SpellcheckHunspellDictionary(