The problem is that DisplayRefreshMonitorManager::createMonitorForClient() always creates a new one for RenderingUpdateScheduler because it's not notified of the window screen change. So, createDisplayRefreshMonitor() is called every time, which returns a reference of the same object, but it's added to the monitors Vector of DisplayRefreshMonitorManager and never removed from there.
Created attachment 385956 [details] Patch
Comment on attachment 385956 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=385956&action=review > Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/DrawingAreaCoordinatedGraphics.cpp:574 > + changeWindowScreen(); This is problematic, cause the lambda is using m_layerTreeHost which is null.
Comment on attachment 385956 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=385956&action=review >> Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/DrawingAreaCoordinatedGraphics.cpp:574 >> + changeWindowScreen(); > > This is problematic, cause the lambda is using m_layerTreeHost which is null. This is called right after setting m_layerTreeHost, or does the lambda capture the value at the time it's declared, even when a reference is passed? It's not crashing here, for sure.
Created attachment 386083 [details] Try to fix wincairo build
Committed r253744: <https://trac.webkit.org/changeset/253744>