AMessage post方法的处理流程

Amessage post方法的处理流程
1.AMessage::post(int64_t delayUs)
  call gLooperRoster.postMessage(this, delayUs)
  
2.ALooperRoster::postMessage
  call postMessage_l(msg, delayUs)
  
3.ALooperRoster::postMessage_l
  call looper->post(msg, delayUs)
  
4.ALooper::post
  call mEventQueue.insert(it, event);
  insert message into mEventQueue list
  
Event的定义：
struct Event {
    int64_t mWhenUs;
    sp<AMessage> mMessage;
};


mEventQueue的声明：
List<Event> mEventQueue;