Add a dirty bit for updateDescendantDependentFlags.

Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 56 matching lines @@
 
 DeprecatedPaintLayerCompositor::DeprecatedPaintLayerCompositor(LayoutView& layoutView)
     : m_layoutView(layoutView)
     , m_compositingReasonFinder(layoutView)
     , m_pendingUpdateType(CompositingUpdateNone)
     , m_hasAcceleratedCompositing(true)
     , m_compositing(false)
     , m_rootShouldAlwaysCompositeDirty(true)
     , m_needsUpdateFixedBackground(false)
     , m_isTrackingPaintInvalidations(false)
+    , m_inOverlayFullscreenVideo(false)
+    , m_needsUpdateDescendantDependentFlags(false)
     , m_rootLayerAttachment(RootLayerUnattached)
-    , m_inOverlayFullscreenVideo(false)
 {
     updateAcceleratedCompositingSettings();
 }
 
 DeprecatedPaintLayerCompositor::~DeprecatedPaintLayerCompositor()
 {
     ASSERT(m_rootLayerAttachment == RootLayerUnattached);
 }
 
 bool DeprecatedPaintLayerCompositor::inCompositingMode() const
@@ skipping 86 matching lines @@
     // Get the current fullscreen element from the document.
     fullscreenElement = Fullscreen::currentFullScreenElementFrom(*contentDocument);
     if (!isHTMLVideoElement(fullscreenElement))
         return 0;
     LayoutObject* layoutObject = fullscreenElement->layoutObject();
     if (!layoutObject)
         return 0;
     return toLayoutVideo(layoutObject);
 }
 
+// The descendant-dependent flags system is badly broken because we clean dirty
+// bits in upward tree walks, which means we need to call updateDescendantDependentFlags
+// at every node in the tree to fully clean all the dirty bits. While we'll in
+// the process of fixing this issue, updateDescendantDependentFlagsForEntireSubtree
+// provides a big hammer for actually cleaning all the dirty bits in a subtree.
+//
+// FIXME: Remove this function once the descendant-dependent flags system keeps
+// its dirty bits scoped to subtrees.
+void updateDescendantDependentFlagsForEntireSubtree(DeprecatedPaintLayer& layer)
+{
+    layer.updateDescendantDependentFlags();
+
+    for (DeprecatedPaintLayer* child = layer.firstChild(); child; child = child->nextSibling())
+        updateDescendantDependentFlagsForEntireSubtree(*child);
+}
+
 void DeprecatedPaintLayerCompositor::updateIfNeededRecursive()
 {
     for (Frame* child = m_layoutView.frameView()->frame().tree().firstChild(); child; child = child->tree().nextSibling()) {
         if (!child->isLocalFrame())
             continue;
         LocalFrame* localFrame = toLocalFrame(child);
         // It's possible for trusted Pepper plugins to force hit testing in situations where
         // the frame tree is in an inconsistent state, such as in the middle of frame detach.
         // TODO(bbudge) Remove this check when trusted Pepper plugins are gone.
         if (localFrame->document()->isActive())
             localFrame->contentLayoutObject()->compositor()->updateIfNeededRecursive();
     }
 
     TRACE_EVENT0("blink", "DeprecatedPaintLayerCompositor::updateIfNeededRecursive");
 
     ASSERT(!m_layoutView.needsLayout());
 
     ScriptForbiddenScope forbidScript;
 
     // FIXME: enableCompositingModeIfNeeded can trigger a CompositingUpdateRebuildTree,
     // which asserts that it's not InCompositingUpdate.
     enableCompositingModeIfNeeded();
 
-    rootLayer()->updateDescendantDependentFlagsForEntireSubtree();
+    if (m_needsUpdateDescendantDependentFlags) {
+        updateDescendantDependentFlagsForEntireSubtree(*rootLayer());
+        m_needsUpdateDescendantDependentFlags = false;
+    }
+
     m_layoutView.commitPendingSelection();
 
     lifecycle().advanceTo(DocumentLifecycle::InCompositingUpdate);
     updateIfNeeded();
     lifecycle().advanceTo(DocumentLifecycle::CompositingClean);
 
     DocumentAnimations::updateCompositorAnimations(m_layoutView.document());
 
     m_layoutView.frameView()->updateCompositorScrollAnimations();
     if (const FrameView::ScrollableAreaSet* animatingScrollableAreas = m_layoutView.frameView()->animatingScrollableAreas()) {
@@ skipping 966 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink