Add support for printing multicol containers, and enable it.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 20 matching lines @@
 #include "core/html/HTMLIFrameElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutFlowThread.h"
 #include "core/layout/LayoutGeometryMap.h"
 #include "core/layout/LayoutMedia.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutQuote.h"
 #include "core/layout/LayoutScrollbarPart.h"
+#include "core/layout/ViewFragmentationContext.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/page/Page.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/ViewPainter.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "platform/TraceEvent.h"
 #include "platform/TracedValue.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/TransformState.h"
 #include "platform/graphics/paint/PaintController.h"
@@ skipping 180 matching lines @@
 bool LayoutView::doingFullPaintInvalidation() const
 {
     return m_frameView->needsFullPaintInvalidation();
 }
 
 void LayoutView::layout()
 {
     if (!document().paginated())
         setPageLogicalHeight(0);
 
-    if (shouldUsePrintingLayout())
+    if (shouldUsePrintingLayout()) {
         m_minPreferredLogicalWidth = m_maxPreferredLogicalWidth = logicalWidth();
+        // TODO(mstensho): Get rid of m_pageLogicalHeight zero check. Currently, pageProperty() in
+        // PrintContext starts printing with zero height, so we have to cope for now.
+        if (!m_fragmentationContext && m_pageLogicalHeight)
+            m_fragmentationContext = adoptPtr(new ViewFragmentationContext(*this));
+    } else if (m_fragmentationContext) {
+        m_fragmentationContext.clear();
+    }
 
     SubtreeLayoutScope layoutScope(*this);
 
     LayoutRect oldLayoutOverflowRect = layoutOverflowRect();
 
     // Use calcWidth/Height to get the new width/height, since this will take the full page zoom factor into account.
     bool relayoutChildren = !shouldUsePrintingLayout() && (!m_frameView
         || logicalWidth() != viewLogicalWidthForBoxSizing()
         || logicalHeight() != viewLogicalHeightForBoxSizing());
     if (relayoutChildren) {
@@ skipping 745 matching lines @@
 }
 
 void LayoutView::sendMediaPositionChangeNotifications(const IntRect& visibleRect)
 {
     for (auto& media : m_mediaForPositionNotification) {
         media->notifyPositionMayHaveChanged(visibleRect);
     }
 }
 
 } // namespace blink