Disentangle updating the ScrollingCoordinator from RenderLayerCompositor

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 18fd498f449bbd6c4ea1fea6390007f59ac465c1..812e7a74abd460ddbb9a9902fe6026e9ae487e67 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -2832,7 +2832,14 @@ void FrameView::updateLayoutAndStyleForPainting()
 
     if (RenderView* view = renderView()) {
         InspectorInstrumentation::willUpdateLayerTree(view->frame());
+
         view->compositor()->updateIfNeededRecursive();
+
+        // FIXME: Is it really possible to be inCompositingMode and not have a ScrollingCoordinator?

[ojan, 2014/06/12 03:49:57]

I tried removing the inCompositingMode check once and tests did fail. If you can
remove it and tests don't fail, then I think we're OK. FWIW, this is one of the
few cases where the inCompositingMode bit is actually not stale. Nearly
everywhere else we read it we have no guarantee that it's not stale. I think we
need to change nearly every caller of this function and the
staleInCompositingMode function to do something else.

+        // FIXME: Is it really possible to have a RenderView and not have a Page?

[ojan, 2014/06/12 03:49:57]

I don't think so. This code is littered with impossible defensive code. I've
removed a bunch of such things.

[ojan, 2014/06/12 03:49:57]

I don't think so. This code is littered with impossible defensive code. I've
removed a bunch of such things.

+        if (view->compositor()->inCompositingMode() && m_frame->isMainFrame() && m_frame->page() && m_frame->page()->scrollingCoordinator())
+            m_frame->page()->scrollingCoordinator()->updateAfterCompositingChangeIfNeeded();
+
         InspectorInstrumentation::didUpdateLayerTree(view->frame());
     }