SPv2: Paint SVG images and self-contained recorded pictures with their own trees.

third_party/WebKit/Source/platform/graphics/paint/ScrollPaintPropertyNode.h

 // Copyright 2016 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 ScrollPaintPropertyNode_h
 #define ScrollPaintPropertyNode_h
 
 #include "platform/PlatformExport.h"
 #include "platform/geometry/FloatSize.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
@@ skipping 12 matching lines @@
 // A scroll node contains auxiliary scrolling information for threaded scrolling
 // which includes how far an area can be scrolled, which transform node contains
 // the scroll offset, etc.
 //
 // Main thread scrolling reasons force scroll updates to go to the main thread
 // and can have dependencies on other nodes. For example, all parents of a
 // scroll node with background attachment fixed set should also have it set.
 class PLATFORM_EXPORT ScrollPaintPropertyNode
     : public RefCounted<ScrollPaintPropertyNode> {
  public:
+  // This node is really a sentinel, and does not represent a real scroll.
   static ScrollPaintPropertyNode* root();
 
   static PassRefPtr<ScrollPaintPropertyNode> create(
       PassRefPtr<const ScrollPaintPropertyNode> parent,
       PassRefPtr<const TransformPaintPropertyNode> scrollOffsetTranslation,
       const IntSize& clip,
       const IntSize& bounds,
       bool userScrollableHorizontal,
       bool userScrollableVertical,
       MainThreadScrollingReasons mainThreadScrollingReasons) {
@@ skipping 111 matching lines @@
   MainThreadScrollingReasons m_mainThreadScrollingReasons;
 };
 
 // Redeclared here to avoid ODR issues.
 // See platform/testing/PaintPrinters.h.
 void PrintTo(const ScrollPaintPropertyNode&, std::ostream*);
 
 }  // namespace blink
 
 #endif  // ScrollPaintPropertyNode_h