Handle nested position:sticky elements correctly (compositor)

cc/blink/web_layer_impl.cc

 // Copyright 2014 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.
 
 #include "cc/blink/web_layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 360 matching lines @@
   web_constraint.leftOffset = constraint.left_offset;
   web_constraint.rightOffset = constraint.right_offset;
   web_constraint.topOffset = constraint.top_offset;
   web_constraint.bottomOffset = constraint.bottom_offset;
   web_constraint.parentRelativeStickyBoxOffset =
       constraint.parent_relative_sticky_box_offset;
   web_constraint.scrollContainerRelativeStickyBoxRect =
       constraint.scroll_container_relative_sticky_box_rect;
   web_constraint.scrollContainerRelativeContainingBlockRect =
       constraint.scroll_container_relative_containing_block_rect;
+  // TODO(smcgruer): Copy over ancestor pointers, or use layer ids.
+  web_constraint.localStickyOffset =
+      blink::WebFloatSize(constraint.local_sticky_offset);
   return web_constraint;
 }
 static cc::LayerStickyPositionConstraint ToStickyPositionConstraint(
     const blink::WebLayerStickyPositionConstraint& web_constraint) {
   cc::LayerStickyPositionConstraint constraint;
   constraint.is_sticky = web_constraint.isSticky;
   constraint.is_anchored_left = web_constraint.isAnchoredLeft;
   constraint.is_anchored_right = web_constraint.isAnchoredRight;
   constraint.is_anchored_top = web_constraint.isAnchoredTop;
   constraint.is_anchored_bottom = web_constraint.isAnchoredBottom;
   constraint.left_offset = web_constraint.leftOffset;
   constraint.right_offset = web_constraint.rightOffset;
   constraint.top_offset = web_constraint.topOffset;
   constraint.bottom_offset = web_constraint.bottomOffset;
   constraint.parent_relative_sticky_box_offset =
       web_constraint.parentRelativeStickyBoxOffset;
   constraint.scroll_container_relative_sticky_box_rect =
       web_constraint.scrollContainerRelativeStickyBoxRect;
   constraint.scroll_container_relative_containing_block_rect =
       web_constraint.scrollContainerRelativeContainingBlockRect;
+  constraint.nearest_layer_shifting_sticky_box =
+      web_constraint.nearestLayerShiftingStickyBox
+          ? web_constraint.nearestLayerShiftingStickyBox->ccLayer()
+          : nullptr;
+  constraint.nearest_layer_shifting_containing_block =
+      web_constraint.nearestLayerShiftingContainingBlock
+          ? web_constraint.nearestLayerShiftingContainingBlock->ccLayer()
+          : nullptr;
+  constraint.local_sticky_offset = web_constraint.localStickyOffset;
   return constraint;
 }
 void WebLayerImpl::setStickyPositionConstraint(
     const blink::WebLayerStickyPositionConstraint& constraint) {
   layer_->SetStickyPositionConstraint(ToStickyPositionConstraint(constraint));
 }
 blink::WebLayerStickyPositionConstraint WebLayerImpl::stickyPositionConstraint()
     const {
   return ToWebLayerStickyPositionConstraint(
       layer_->sticky_position_constraint());
@@ skipping 66 matching lines @@
 
 void WebLayerImpl::setPreferredRasterBounds(const WebSize& bounds) {
   layer_->SetPreferredRasterBounds(bounds);
 }
 
 void WebLayerImpl::clearPreferredRasterBounds() {
   layer_->ClearPreferredRasterBounds();
 }
 
 }  // namespace cc_blink