webview can not scroll when using WebKit2UseRemoteLayerTreeDrawingArea


RemoteLayerTreeDrawingArea
    bool usesDelegatedScrolling() const override { return true; }
    bool usesDelegatedPageScaling() const override { return true; }

usesDelegatedScrolling return true, but ui side not impl scrollview and scroll function

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void PageClientImpl::requestScroll(const FloatPoint& scrollPosition, const IntPoint& scrollOrigin, ScrollIsAnimated)
{
}

WebCore::FloatPoint PageClientImpl::viewScrollPosition()
{
    return { };
}

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so the function "scrollingTree().setNeedsApplyLayerPositionsAfterCommit();" is not called when scroll event fired