persistent_no_trace.cpp:9:1: warning: [blink-gc] Class 'HeapObject' has untraced or not traceable fields.
void HeapObject::Trace(Visitor* visitor) {
^
./persistent_no_trace.h:16:5: note: [blink-gc] Untraceable field 'm_crossThreadPersistent' declared here:
    CrossThreadPersistent<HeapObject> m_crossThreadPersistent;
    ^
./persistent_no_trace.h:17:5: note: [blink-gc] Untraceable field 'm_crossThreadWeakPersistent' declared here:
    CrossThreadWeakPersistent<HeapObject> m_crossThreadWeakPersistent;
    ^
1 warning generated.