With PSON, when there's a history navigation the WebPage replaces the drawing area with a new one. In case of coordinated graphics, the new drawing area ends up using the wrong display refresh monitor because DrawingArea::createDisplayRefreshMonitor() is not called. We call WebPage::windowScreenDidChange() after creating the LayerTreeHost to ensure DrawingArea::createDisplayRefreshMonitor() is called, but in this case the page is the same, and the displayID hasn't really changed. So, we need to ensure that the displayID we create is not based on WebPage unique identifier, but on DrawingArea's because the ThreadedDisplayRefreshMonitor needs to be created for every DrawingArea, not WebPage.