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

base/trace_event/trace_event_memory_overhead.cc

Index: base/trace_event/trace_event_memory_overhead.cc
diff --git a/base/trace_event/trace_event_memory_overhead.cc b/base/trace_event/trace_event_memory_overhead.cc
index ba7207d616360e2409ca14fd0d8b5a49ffcb52b4..23579cbb22da32d1b745141e425b02084829d9d2 100644
--- a/base/trace_event/trace_event_memory_overhead.cc
+++ b/base/trace_event/trace_event_memory_overhead.cc
@@ -104,7 +104,7 @@ void TraceEventMemoryOverhead::AddValue(const Value& value) {
       const ListValue* list_value = nullptr;
       value.GetAsList(&list_value);
       Add("ListValue", sizeof(ListValue));
-      for (const Value* v : *list_value)
+      for (const auto& v : *list_value)
         AddValue(*v);
     } break;