Fix shouldPaint issue when a composited floating iframe becomes non-self-painting

third_party/WebKit/Source/core/layout/FloatingObjects.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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 11 matching lines @@
  * Boston, MA 02110-1301, USA.
  */
 
 #include "core/layout/FloatingObjects.h"
 
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/api/LineLayoutBlockFlow.h"
 #include "core/layout/shapes/ShapeOutsideInfo.h"
-#include "core/paint/PaintLayer.h"
-#include "platform/RuntimeEnabledFeatures.h"
 #include "wtf/PtrUtil.h"
 #include <algorithm>
 #include <memory>
 
 using namespace WTF;
 
 namespace blink {
 
 struct SameSizeAsFloatingObject {
   void* pointers[2];
@@ skipping 27 matching lines @@
 FloatingObject::FloatingObject(LayoutBox* layoutObject,
                                Type type,
                                const LayoutRect& frameRect,
                                bool shouldPaint,
                                bool isDescendant,
                                bool isLowestNonOverhangingFloatInChild)
     : m_layoutObject(layoutObject),
       m_originatingLine(nullptr),
       m_frameRect(frameRect),
       m_type(type),
+      m_shouldPaint(shouldPaint),
       m_isDescendant(isDescendant),
       m_isPlaced(true),
       m_isLowestNonOverhangingFloatInChild(isLowestNonOverhangingFloatInChild)
 #if DCHECK_IS_ON()
       ,
       m_isInPlacedTree(false)
 #endif
 {
-  m_shouldPaint = shouldPaint || shouldPaintForCompositedLayoutPart();
-}
-
-bool FloatingObject::shouldPaintForCompositedLayoutPart() {
-  // HACK: only non-self-painting floats should paint. However, due to the
-  // fundamental compositing bug, some LayoutPart objects may become
-  // self-painting due to being composited. This leads to a chicken-egg issue
-  // because layout may not depend on compositing.
-  // If this is the case, set shouldPaint() to true even if the layer is
-  // technically self-painting. This lets the float which contains a LayoutPart
-  // start painting as soon as it stops being composited, without having to
-  // re-layout the float.
-  // This hack can be removed after SPv2.
-  return m_layoutObject->layer() &&
-         m_layoutObject->layer()->isSelfPaintingOnlyBecauseIsCompositedPart() &&
-         !RuntimeEnabledFeatures::slimmingPaintV2Enabled();
 }
 
 std::unique_ptr<FloatingObject> FloatingObject::create(
     LayoutBox* layoutObject) {
   std::unique_ptr<FloatingObject> newObj =
       WTF::wrapUnique(new FloatingObject(layoutObject));
 
   // If a layer exists, the float will paint itself. Otherwise someone else
   // will.
-  newObj->setShouldPaint(!layoutObject->hasSelfPaintingLayer() ||
-                         newObj->shouldPaintForCompositedLayoutPart());
+  newObj->setShouldPaint(!layoutObject->hasSelfPaintingLayer());
 
   newObj->setIsDescendant(true);
 
   return newObj;
 }
 
-bool FloatingObject::shouldPaint() const {
-  return m_shouldPaint && !m_layoutObject->hasSelfPaintingLayer();
-}
-
 std::unique_ptr<FloatingObject> FloatingObject::copyToNewContainer(
     LayoutSize offset,
     bool shouldPaint,
     bool isDescendant) const {
   return WTF::wrapUnique(new FloatingObject(
       layoutObject(), getType(),
       LayoutRect(frameRect().location() - offset, frameRect().size()),
       shouldPaint, isDescendant, isLowestNonOverhangingFloatInChild()));
 }
 
@@ skipping 612 matching lines @@
     const FloatingObject* floatingObject) {
   return String::format("%p (%gx%g %gx%g)", floatingObject,
                         floatingObject->frameRect().x().toFloat(),
                         floatingObject->frameRect().y().toFloat(),
                         floatingObject->frameRect().maxX().toFloat(),
                         floatingObject->frameRect().maxY().toFloat());
 }
 #endif
 
 }  // namespace blink