Remove scroll_clip_layer dependency from viewport layer tracking

third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp

Index: third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
index 33a2f69487485dd49744c67b838852ac94842244..cae6c5ac90f47ff3f85f5707f07ba8a86942806a 100644
--- a/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.cpp
@@ -202,6 +202,18 @@ GraphicsLayer* TopDocumentRootScrollerController::RootScrollerLayer() const {
   return graphics_layer;
 }
 
+GraphicsLayer* TopDocumentRootScrollerController::RootContainerLayer() const {
+  ScrollableArea* area =
+      RootScrollerUtil::ScrollableAreaForRootScroller(global_root_scroller_);
+

[wkorman, 2017/05/17 20:59:39]

Can shorten below here to just:

return area ? area->LayerForContainer() : nullptr;

[pdr., 2017/05/17 21:36:44]

Done

+  if (!area)
+    return nullptr;
+
+  GraphicsLayer* graphics_layer = area->LayerForContainer();
+
+  return graphics_layer;
+}
+
 PaintLayer* TopDocumentRootScrollerController::RootScrollerPaintLayer() const {
   return RootScrollerUtil::PaintLayerForRootScroller(global_root_scroller_);
 }