Don't coerce pointers to compositor layer mappings to booleans.

Source/core/rendering/RenderLayerRepainter.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 117 matching lines @@
     ASSERT(m_repaintStatus == NeedsFullRepaintForPositionedMovementLayout);
     return m_renderer->compositingState() != PaintsIntoOwnBacking;
 }
 
 // Since we're only painting non-composited layers, we know that they all share the same repaintContainer.
 void RenderLayerRepainter::repaintIncludingNonCompositingDescendants(RenderLayerModelObject* repaintContainer)
 {
     m_renderer->repaintUsingContainer(repaintContainer, pixelSnappedIntRect(m_renderer->clippedOverflowRectForRepaint(repaintContainer)));
 
     for (RenderLayer* curr = m_renderer->layer()->firstChild(); curr; curr = curr->nextSibling()) {
-        if (!curr->compositedLayerMapping())
+        // FIXME: we also want to paint those layers who have a backing but paint into
+        // our repaint container.
+        if (curr->compositingState() == NotComposited)

[shawnsingh, 2013/11/12 09:55:50]

I don't understand this FIXME... why cant we just write:
  if (curr->compositingState() == NotComposited || curr->compositingState() ==
HasOwnBackingButPaintsIntoAncestor)

which would be equivalent to the previous code, and address your FIXME all at
the same time?

[Ian Vollick, 2013/11/14 04:12:47]

Ah right. We want to paint those layers that paint into our repaint container,
but I was worried that the paints-into-ancestor layers may paint into some other
container (is that impossible? seems quite possible in the world of squashing).
I put the FIXME here so I could add the container comparison code in another
patch.

             curr->repainter().repaintIncludingNonCompositingDescendants(repaintContainer);
     }
 }
 
 LayoutRect RenderLayerRepainter::repaintRectIncludingNonCompositingDescendants() const
 {
     LayoutRect repaintRect = m_repaintRect;
     for (RenderLayer* child = m_renderer->layer()->firstChild(); child; child = child->nextSibling()) {
         // Don't include repaint rects for composited child layers; they will paint themselves and have a different origin.
-        if (child->compositedLayerMapping())
+        // FIXME: we also want to include those layers who have a backing but paint into
+        // our repaint container.
+        if (child->compositingState() != NotComposited)

[shawnsingh, 2013/11/12 09:55:50]

This code doesn't seem to require a FIXME, either?

[Ian Vollick, 2013/11/14 04:12:47]

Same as above.

             continue;
 
         repaintRect.unite(child->repainter().repaintRectIncludingNonCompositingDescendants());
     }
     return repaintRect;
 }
 
 void RenderLayerRepainter::setBackingNeedsRepaint()
 {
-    ASSERT(m_renderer->compositedLayerMapping());
+    ASSERT(m_renderer->hasCompositedLayerMapping());
     m_renderer->compositedLayerMapping()->setContentsNeedDisplay();
 }
 
 void RenderLayerRepainter::setBackingNeedsRepaintInRect(const LayoutRect& r)
 {
     // https://bugs.webkit.org/show_bug.cgi?id=61159 describes an unreproducible crash here,
     // so assert but check that the layer is composited.
-    ASSERT(m_renderer->compositedLayerMapping());
-    if (!m_renderer->compositedLayerMapping()) {
+    ASSERT(m_renderer->hasCompositedLayerMapping());
+    if (!m_renderer->hasCompositedLayerMapping()) {
         // If we're trying to repaint the placeholder document layer, propagate the
         // repaint to the native view system.
         LayoutRect absRect(r);
         LayoutPoint delta;
         m_renderer->layer()->convertToLayerCoords(m_renderer->layer()->root(), delta);
         absRect.moveBy(delta);
 
         RenderView* view = m_renderer->view();
         if (view)
             view->repaintViewRectangle(absRect);
@@ skipping 27 matching lines @@
         // shader can address any ouput pixel.
         // Note: This is only for output rect, so there's no need to expand the dirty source rect.
         rectForRepaint.unite(m_renderer->layer()->calculateLayerBounds(m_renderer->layer()));
     }
 
     RenderLayer* parentLayer = enclosingFilterRepaintLayer();
     ASSERT(parentLayer);
     FloatQuad repaintQuad(rectForRepaint);
     LayoutRect parentLayerRect = m_renderer->localToContainerQuad(repaintQuad, parentLayer->renderer()).enclosingBoundingBox();
 
-    if (parentLayer->compositedLayerMapping()) {
+    if (parentLayer->compositingState() == PaintsIntoOwnBacking) {
         parentLayer->repainter().setBackingNeedsRepaintInRect(parentLayerRect);
         return;
     }
 
     if (parentLayer->paintsWithFilters()) {
         parentLayer->repainter().setFilterBackendNeedsRepaintingInRect(parentLayerRect);
         return;
     }
 
     if (parentLayer->isRootLayer()) {
         RenderView* view = toRenderView(parentLayer->renderer());
         view->repaintViewRectangle(parentLayerRect);
         return;
     }
 
     ASSERT_NOT_REACHED();
 }
 
 RenderLayer* RenderLayerRepainter::enclosingFilterRepaintLayer() const
 {
     for (const RenderLayer* curr = m_renderer->layer(); curr; curr = curr->parent()) {
         if ((curr != m_renderer->layer() && curr->requiresFullLayerImageForFilters()) || curr->compositingState() == PaintsIntoOwnBacking || curr->isRootLayer())
             return const_cast<RenderLayer*>(curr);
     }
     return 0;
 }
 
 } // Namespace WebCore