void BufferQueueCore::clearBufferSlotLocked(int slot) {
    BQ_LOGV("clearBufferSlotLocked: slot %d", slot);

    mSlots[slot].mGraphicBuffer.clear();
    mSlots[slot].mBufferState.reset();
    mSlots[slot].mRequestBufferCalled = false;
    mSlots[slot].mFrameNumber = 0;
    mSlots[slot].mAcquireCalled = false;
    mSlots[slot].mNeedsReallocation = true;

    // Destroy fence as BufferQueue now takes ownership
    if (mSlots[slot].mEglFence != EGL_NO_SYNC_KHR) {
        eglDestroySyncKHR(mSlots[slot].mEglDisplay, mSlots[slot].mEglFence);
        mSlots[slot].mEglFence = EGL_NO_SYNC_KHR;
    }
    mSlots[slot].mFence = Fence::NO_FENCE;
    mSlots[slot].mEglDisplay = EGL_NO_DISPLAY;

    if (mLastQueuedSlot == slot) {
        mLastQueuedSlot = INVALID_BUFFER_SLOT;
    }
}

清理指定 BufferSlot。