void SurfaceComposerClient::Transaction::clear() {
    mComposerStates.clear();
    mDisplayStates.clear();
    mListenerCallbacks.clear();
    mInputWindowCommands.clear();
    mContainsBuffer = false;
    mForceSynchronous = 0;
    mTransactionNestCount = 0;
    mAnimation = false;
    mEarlyWakeupStart = false;
    mEarlyWakeupEnd = false;
    mDesiredPresentTime = 0;
    mIsAutoTimestamp = true;
    mFrameTimelineInfo.clear();
    mApplyToken = nullptr;
}

清除 mListenerCallbacks。这里会递减对 SurfaceControl 的强引用计数，它对应在 Transaction::registerSurfaceControlForCallback() 中递增的强引用计数。