Rewrite blink->cc scroll offset logic for SPV2

third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h

Index: third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h
diff --git a/third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h b/third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h
index 866b859d89b367d40d2a23aa60df988b3f4c0ecb..b3d37649dffddf7ec8d6dd0d014181fad6427291 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.h
@@ -75,6 +75,10 @@ class PropertyTreeManager {
 
   int ensureCompositorTransformNode(const TransformPaintPropertyNode*);
   int ensureCompositorClipNode(const ClipPaintPropertyNode*);
+  // If a new compositor scroll node is created, this also handles updating
+  // the associated compositor transform node's scroll properties. Blink's
+  // transform nodes are used for scroll offset whereas cc's transform nodes
+  // store the scroll offset in a separate field.
   int ensureCompositorScrollNode(const ScrollPaintPropertyNode*);
 
   int switchToEffectNode(const EffectPaintPropertyNode& nextEffect);
@@ -82,9 +86,6 @@ class PropertyTreeManager {
     return m_effectStack.back().id;
   }
 
-  // Scroll offset has special treatment in the transform and scroll trees.
-  void updateScrollOffset(int layerId, int scrollId);
-
  private:
   void buildEffectNodesRecursively(const EffectPaintPropertyNode* nextEffect);