调用 SurfaceFlinger 的 removeGraphicBufferProducerAsync()，通知生产者销毁了。

MonitoredProducer::~MonitoredProducer() {
    // Remove ourselves from SurfaceFlinger's list. We do this asynchronously
    // because we don't know where this destructor is called from. It could be
    // called with the mStateLock held, leading to a dead-lock (it actually
    // happens).
    mFlinger->removeGraphicBufferProducerAsync(onAsBinder());
}

IBinder* MonitoredProducer::onAsBinder() {
    return this;
}