void FullscreenElementStack::setFullScreenRenderer(RenderFullScreen* renderer)
{
    if (renderer == m_fullScreenRenderer)
        return;

    if (renderer && m_savedPlaceholderRenderStyle) {
        renderer->createPlaceholder(m_savedPlaceholderRenderStyle.release(), m_savedPlaceholderFrameRect);
    } else if (renderer && m_fullScreenRenderer && m_fullScreenRenderer->placeholder()) {
        RenderBlock* placeholder = m_fullScreenRenderer->placeholder();
        renderer->createPlaceholder(RenderStyle::clone(placeholder->style()), placeholder->frameRect());
    }

    if (m_fullScreenRenderer)
        m_fullScreenRenderer->destroy();
    ASSERT(!m_fullScreenRenderer);

    m_fullScreenRenderer = renderer;
}