1 files changed, 9 insertions, 0 deletions
diff --git a/Source/WebKit2/UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.cpp b/Source/WebKit2/UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.cpp
index de1f0af8e..ddef49d05 100644
--- a/Source/WebKit2/UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.cpp
+++ b/Source/WebKit2/UIProcess/CoordinatedGraphics/CoordinatedLayerTreeHostProxy.cpp
@@ -72,6 +72,15 @@ void CoordinatedLayerTreeHostProxy::commitCoordinatedGraphicsState(const Coordin
 
 void CoordinatedLayerTreeHostProxy::setVisibleContentsRect(const FloatRect& rect, const FloatPoint& trajectoryVector)
 {
+#if PLATFORM(QT)
+    // Inform the renderer to adjust viewport-fixed layers.
+    RefPtr<CoordinatedGraphicsScene> sceneProtector(m_scene);
+    const FloatPoint& scrollPosition = rect.location();
+    dispatchUpdate([=] {
+        sceneProtector->setScrollPosition(scrollPosition);
+    });
+#endif
+
     if (rect == m_lastSentVisibleRect && trajectoryVector == m_lastSentTrajectoryVector)
         return;