WIP: Construct SPV2's scroll paint property tree

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h

 // Copyright 2015 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 PaintPropertyTreeBuilder_h
 #define PaintPropertyTreeBuilder_h
 
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
+#include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class FrameView;
 class LayoutObject;
 class ObjectPaintProperties;
 
 // The context for PaintPropertyTreeBuilder.
@@ skipping 15 matching lines @@
         // to immediate children.
         bool shouldFlattenInheritedTransform = false;
         // Rendering context for 3D sorting. See
         // TransformPaintPropertyNode::renderingContextID.
         unsigned renderingContextID = 0;
         // The clip node describes the accumulated raster clip for the current subtree.
         // Note that the computed raster region in canvas space for a clip node is independent from
         // the transform and paint offset above. Also the actual raster region may be affected
         // by layerization and occlusion tracking.
         const ClipPaintPropertyNode* clip = nullptr;
+        // The scroll node contains information for compositor-thread scrolling such as the
+        // scrolling hierarchy, the extent that can be scrolled, etc. Because scroll nodes reference
+        // a scroll offset transform, scroll nodes should be updated if the transform tree changes.
+        const ScrollPaintPropertyNode* scroll = nullptr;
     };
 
     ContainingBlockContext current;
 
     // Separate context for out-of-flow positioned and fixed positioned elements are needed
     // because they don't use DOM parent as their containing block.
     // These additional contexts normally pass through untouched, and are only copied from
     // the main context when the current element serves as the containing block of corresponding
     // positioned descendants.
     // Overflow clips are also inherited by containing block tree instead of DOM tree, thus they
@@ skipping 23 matching lines @@
 private:
     static void updatePaintOffsetTranslation(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateTransform(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateEffect(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateCssClip(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateLocalBorderBoxContext(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateScrollbarPaintOffset(const LayoutObject&, const PaintPropertyTreeBuilderContext&);
     static void updateOverflowClip(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updatePerspective(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateSvgLocalToBorderBoxTransform(const LayoutObject&, PaintPropertyTreeBuilderContext&);
-    static void updateScrollTranslation(const LayoutObject&, PaintPropertyTreeBuilderContext&);
+    static void updateScrollAndScrollTranslation(const LayoutObject&, PaintPropertyTreeBuilderContext&);
     static void updateOutOfFlowContext(const LayoutObject&, PaintPropertyTreeBuilderContext&);
 };
 
 } // namespace blink
 
 #endif // PaintPropertyTreeBuilder_h