Add static root property tree nodes [spv2]

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 35 matching lines @@
         DCHECK(scrollOffsetTranslation->matrix().isIdentityOr2DTranslation());
         m_scrollOffsetTranslation = scrollOffsetTranslation;
         m_clip = clip;
         m_bounds = bounds;
         m_userScrollableHorizontal = userScrollableHorizontal;
         m_userScrollableVertical = userScrollableVertical;
         m_mainThreadScrollingReasons = 0;
     }
 
     ScrollPaintPropertyNode* parent() const { return m_parent.get(); }
+    bool isRoot() const { return !m_parent; }
 
     // Transform that the scroll is relative to.
     const TransformPaintPropertyNode* scrollOffsetTranslation() const { return m_scrollOffsetTranslation.get(); }
 
     // The clipped area that contains the scrolled content.
     const IntSize& clip() const { return m_clip; }
 
     // The bounds of the content that is scrolled within |clip|.
     const IntSize& bounds() const { return m_bounds; }
 
     bool userScrollableHorizontal() const { return m_userScrollableHorizontal; }
     bool userScrollableVertical() const { return m_userScrollableVertical; }
 
     // Return reason bitfield with values from cc::MainThreadScrollingReason.
     MainThreadScrollingReasons mainThreadScrollingReasons() const
     {
         return m_mainThreadScrollingReasons;
     }
     bool hasMainThreadScrollingReasons(MainThreadScrollingReasons reasons) const
     {
         return m_mainThreadScrollingReasons & reasons;
     }
     void addMainThreadScrollingReasons(MainThreadScrollingReasons reasons)
     {
         m_mainThreadScrollingReasons |= reasons;
     }
+    void clearMainThreadScrollingReasons()
+    {
+        m_mainThreadScrollingReasons = 0;
+    }
 
 private:
     ScrollPaintPropertyNode(
         PassRefPtr<ScrollPaintPropertyNode> parent,
         PassRefPtr<const TransformPaintPropertyNode> scrollOffsetTranslation,
         IntSize clip,
         IntSize bounds,
         bool userScrollableHorizontal,
         bool userScrollableVertical)
         : m_parent(parent)
@@ skipping 19 matching lines @@
     // TODO(pdr): Add a bit for whether this is affected by page scale.
 };
 
 // Redeclared here to avoid ODR issues.
 // See platform/testing/PaintPrinters.h.
 void PrintTo(const ScrollPaintPropertyNode&, std::ostream*);
 
 } // namespace blink
 
 #endif // ScrollPaintPropertyNode_h