[New Multicolumn] Render transformed layers into multiple fragments.

Source/core/paint/LayerPainter.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LayerPainter_h
 #define LayerPainter_h
 
 #include "core/rendering/LayerFragment.h"
 #include "core/rendering/LayerPaintingInfo.h"
 
 namespace blink {
 
 class ClipRect;
 class LayoutPoint;
 class RenderLayer;
 
 class LayerPainter {
 public:
+    enum FragmentPolicy { AllowMultipleFragments, ForceSingleFragment };
+
     LayerPainter(RenderLayer& renderLayer) : m_renderLayer(renderLayer) { }
 
     // The paint() method paints the layers that intersect the damage rect from back to front.
     //  paint() assumes that the caller will clip to the bounds of damageRect if necessary.
     void paint(GraphicsContext*, const LayoutRect& damageRect, PaintBehavior = PaintBehaviorNormal, RenderObject* paintingRoot = 0, PaintLayerFlags = 0);
     // paintLayer() assumes that the caller will clip to the bounds of the painting dirty if necessary.
     void paintLayer(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
     // paintLayerContents() assumes that the caller will clip to the bounds of the painting dirty rect if necessary.
-    void paintLayerContents(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
+    void paintLayerContents(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags, FragmentPolicy = AllowMultipleFragments);
 
     void paintOverlayScrollbars(GraphicsContext*, const LayoutRect& damageRect, PaintBehavior, RenderObject* paintingRoot = 0);
 
 private:
     enum ClipState { HasNotClipped, HasClipped };
 
-    void paintLayerContentsAndReflection(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
+    void paintLayerContentsAndReflection(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags, FragmentPolicy = AllowMultipleFragments);
     void paintLayerWithTransform(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
     void paintFragmentByApplyingTransform(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags, const LayoutPoint& fragmentTranslation);
 
     void paintChildren(unsigned childrenToVisit, GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
     void paintPaginatedChildLayer(RenderLayer* childLayer, GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
     void paintChildLayerIntoColumns(RenderLayer* childLayer, GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags, const Vector<RenderLayer*>& columnLayers, size_t columnIndex);
     bool atLeastOneFragmentIntersectsDamageRect(LayerFragments&, const LayerPaintingInfo&, PaintLayerFlags, const LayoutPoint& offsetFromRoot);
     void paintFragmentWithPhase(PaintPhase, const LayerFragment&, GraphicsContext*, const ClipRect&, const LayerPaintingInfo&, PaintBehavior, RenderObject* paintingRootForRenderer, PaintLayerFlags, ClipState);
     void paintBackgroundForFragments(const LayerFragments&, GraphicsContext*,
         const LayoutRect& transparencyPaintDirtyRect, const LayerPaintingInfo&, PaintBehavior, RenderObject* paintingRootForRenderer, PaintLayerFlags);
@@ skipping 11 matching lines @@
     // Returns whether this layer should be painted during sofware painting (i.e., not via calls from CompositedLayerMapping to draw into composited
     // layers).
     bool shouldPaintLayerInSoftwareMode(const LayerPaintingInfo&, PaintLayerFlags paintFlags);
 
     RenderLayer& m_renderLayer;
 };
 
 } // namespace blink
 
 #endif // LayerPainter_h