Optimize repaint on FrameView resize

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 86 matching lines @@
     BSRight,
     BSBottom,
     BSLeft
 };
 
 enum MarkingBehavior {
     MarkOnlyThis,
     MarkContainingBlockChain,
 };
 
+enum RepaintLayerBehavior {
+    RepaintLayer,
+    DontRepaintLayer,
+};
+
 enum MapCoordinatesMode {
     IsFixed = 1 << 0,
     UseTransforms = 1 << 1,
     ApplyContainerFlip = 1 << 2,
     TraverseDocumentBoundaries = 1 << 3,
 };
 typedef unsigned MapCoordinatesFlags;
 
 const int caretWidth = 1;
 
@@ skipping 487 matching lines @@
     // Returns the object containing this one. Can be different from parent for positioned elements.
     // If repaintContainer and repaintContainerSkipped are not null, on return *repaintContainerSkipped
     // is true if the renderer returned is an ancestor of repaintContainer.
     RenderObject* container(const RenderLayerModelObject* repaintContainer = 0, bool* repaintContainerSkipped = 0) const;
 
     virtual RenderObject* hoverAncestor() const { return parent(); }
 
     Element* offsetParent() const;
 
     void markContainingBlocksForLayout(bool scheduleRelayout = true, RenderObject* newRoot = 0, SubtreeLayoutScope* = 0);
-    void setNeedsLayout(MarkingBehavior = MarkContainingBlockChain, SubtreeLayoutScope* = 0);
+    void setNeedsLayout(MarkingBehavior = MarkContainingBlockChain, SubtreeLayoutScope* = 0, RepaintLayerBehavior = RepaintLayer);
     void clearNeedsLayout();
     void setChildNeedsLayout(MarkingBehavior = MarkContainingBlockChain, SubtreeLayoutScope* = 0);
     void setNeedsPositionedMovementLayout();
     void setNeedsSimplifiedNormalFlowLayout();
     void setPreferredLogicalWidthsDirty(MarkingBehavior = MarkContainingBlockChain);
     void clearPreferredLogicalWidthsDirty();
     void invalidateContainerPreferredLogicalWidths();
 
     void setNeedsLayoutAndPrefWidthsRecalc()
     {
@@ skipping 637 matching lines @@
     if (isText() && !isBR())
         return false;
     return true;
 }
 
 inline bool RenderObject::isBeforeOrAfterContent() const
 {
     return isBeforeContent() || isAfterContent();
 }
 
-inline void RenderObject::setNeedsLayout(MarkingBehavior markParents, SubtreeLayoutScope* layouter)
+inline void RenderObject::setNeedsLayout(MarkingBehavior markParents, SubtreeLayoutScope* layouter, RepaintLayerBehavior repaintLayer)
 {
     ASSERT(!isSetNeedsLayoutForbidden());
     bool alreadyNeededLayout = m_bitfields.selfNeedsLayout();
     setSelfNeedsLayout(true);
     if (!alreadyNeededLayout) {
         if (markParents == MarkContainingBlockChain && (!layouter || layouter->root() != this))
             markContainingBlocksForLayout(true, 0, layouter);
-        if (hasLayer())
+        // FIXME: This may be incorrect, but needed at least because StyleDifferenceLayout implies repaint for now.

[Julien - ping for review, 2014/03/29 01:01:26]

This is not strictly incorrect: it's conservative and in some cases unneeded
which is different AFAICT.

Also this FIXME is not really explaining the 'why' it's required or what we
could do to improve the situation so let's try to improve it:

// StyleDifferenceLayout is used for different cases currently, one of which is
that our content changed which mandates an invalidation.
// FIXME: We should be able to skip this automatic invalidation (see
crbug.com/325569).

[Xianzhu, 2014/03/30 22:26:53]

Done.

+        if (repaintLayer == RepaintLayer && hasLayer())
             setLayerNeedsFullRepaint();
     }
 }
 
 inline void RenderObject::clearNeedsLayout()
 {
     setSelfNeedsLayout(false);
     setEverHadLayout(true);
     setPosChildNeedsLayout(false);
     setNeedsSimplifiedNormalFlowLayout(false);
@@ skipping 135 matching lines @@
 void showTree(const WebCore::RenderObject*);
 void showLineTree(const WebCore::RenderObject*);
 void showRenderTree(const WebCore::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const WebCore::RenderObject* object1, const WebCore::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h