Remove raw DictionaryValue::Set in //components

components/search_engines/default_search_policy_handler.cc

Index: components/search_engines/default_search_policy_handler.cc
diff --git a/components/search_engines/default_search_policy_handler.cc b/components/search_engines/default_search_policy_handler.cc
index 83a356515b00bdc82fe9f39c88feaeba71801ba0..295334d2d0f37a44c6172d724e203f15730e06a8 100644
--- a/components/search_engines/default_search_policy_handler.cc
+++ b/components/search_engines/default_search_policy_handler.cc
@@ -36,7 +36,8 @@ void SetListInPref(const PolicyMap& policies,
     bool is_list = policy_value->GetAsList(&policy_list);
     DCHECK(is_list);
   }
-  dict->Set(key, policy_list ? policy_list->DeepCopy() : new base::ListValue());
+  dict->Set(key, policy_list ? base::MakeUnique<base::ListValue>(*policy_list)
+                             : base::MakeUnique<base::ListValue>());
 }
 
 // Extracts a string from a policy value and adds it to a pref dictionary.