Implement CSS: scroll-boundary-behavior

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index 3f7a58cdc7346e28159fd34c773fd4ea38c416e9..c26c6a2b799fc67b9dae8647d2401d272196efca 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -79,6 +79,7 @@
 #include "platform/wtf/CurrentTime.h"
 #include "platform/wtf/text/StringBuilder.h"
 #include "public/platform/WebLayerStickyPositionConstraint.h"
+#include "public/platform/WebScrollBoundaryBehavior.h"
 
 namespace blink {
 
@@ -1155,11 +1156,27 @@ void CompositedLayerMapping::UpdateGraphicsLayerGeometry(
   UpdateShouldFlattenTransform();
   UpdateChildrenTransform();
   UpdateScrollParent(ScrollParent());
+  UpdateScrollBoundaryBehavior();
   RegisterScrollingLayers();
 
   UpdateCompositingReasons();
 }
 
+void CompositedLayerMapping::UpdateScrollBoundaryBehavior() {
+  EScrollBoundaryBehavior behavior_x =
+      GetLayoutObject().StyleRef().ScrollBoundaryBehaviorX();
+  EScrollBoundaryBehavior behavior_y =
+      GetLayoutObject().StyleRef().ScrollBoundaryBehaviorY();
+  if (scrolling_contents_layer_) {
+    using ScrollBoundaryBehavior =
+        WebScrollBoundaryBehavior::ScrollBoundaryBehaviorType;
+    scrolling_contents_layer_->SetScrollBoundaryBehavior(
+        WebScrollBoundaryBehavior(
+            static_cast<ScrollBoundaryBehavior>(behavior_x),
+            static_cast<ScrollBoundaryBehavior>(behavior_y)));
+  }
+}
+
 void CompositedLayerMapping::UpdateMainGraphicsLayerGeometry(
     const IntRect& relative_compositing_bounds,
     const IntRect& local_compositing_bounds,