Move MaxScrollOffset to property_trees

cc/trees/property_tree_builder.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/trees/property_tree_builder.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <set>
@@ skipping 662 matching lines @@
 
   if (!requires_node) {
     data_for_children->scroll_tree_parent = parent_id;
   } else {
     ScrollNode node;
     node.owner_id = layer->id();
     node.data.scrollable = scrollable;
     node.data.main_thread_scrolling_reasons = main_thread_scrolling_reasons;
     node.data.contains_non_fast_scrollable_region =
         contains_non_fast_scrollable_region;
-    node.data.transform_id =
-        data_for_children->transform_tree_parent->transform_tree_index();
+    gfx::Size clip_bounds;
+    if (layer->scroll_clip_layer()) {
+      clip_bounds = layer->scroll_clip_layer()->bounds();
+      if (layer->scroll_clip_layer()->transform_tree_index() !=
+          kInvalidPropertyTreeNodeId) {

[ajuma, 2016/02/09 22:35:05]

Are there cases where this doesn't hold? What if we DCHECK instead?

[sunxd, 2016/02/09 23:03:56]

In LayerTreeHostImplTest.ScrollUnknownScrollAncestorMismatch, child_scroll_clip
layer is created but not added to the layer tree, so when building property
trees here, child_scroll layer's clip layer does not have a valid
transform_tree_index.

[ajuma, 2016/02/10 00:15:06]

What if we modify the test so that the child_scroll_clip_layer is added to the
tree (in between scroll_layer and child_scroll)?

+        node.data.max_scroll_offset_affected_by_page_scale =
+            !data_from_ancestor.transform_tree
+                 ->Node(layer->scroll_clip_layer()->transform_tree_index())
+                 ->data.in_subtree_of_page_scale_layer &&
+            data_from_ancestor.in_subtree_of_page_scale_layer;
+      }
+    }
+    node.data.scroll_clip_layer_bounds = clip_bounds;
+
+    node.data.is_inner_viewport_scroll_layer =
+        layer == data_from_ancestor.inner_viewport_scroll_layer;
+    node.data.is_outer_viewport_scroll_layer =
+        layer == data_from_ancestor.outer_viewport_scroll_layer;
+
+    node.data.bounds = layer->bounds();
+
     data_for_children->scroll_tree_parent =
         data_for_children->scroll_tree->Insert(node, parent_id);
     data_for_children->main_thread_scrolling_reasons =
         node.data.main_thread_scrolling_reasons;
     data_for_children->scroll_tree_parent_created_by_uninheritable_criteria =
         scroll_node_uninheritable_criteria;
   }
 
   layer->SetScrollTreeIndex(data_for_children->scroll_tree_parent);
 }
@@ skipping 231 matching lines @@
     const gfx::Transform& device_transform,
     PropertyTrees* property_trees) {
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees);
 }
 
 }  // namespace cc