Revert of cc: Move data to LayerTree from LayerTreeHost.

cc/layers/layer.cc

 // Copyright 2010 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/layers/layer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 111 matching lines @@
     DCHECK_EQ(this, inputs_.replica_layer->parent());
     inputs_.replica_layer->RemoveFromParent();
   }
 }
 
 void Layer::SetLayerTreeHost(LayerTreeHost* host) {
   if (layer_tree_host_ == host)
     return;
 
   if (layer_tree_host_) {
-    layer_tree_->property_trees()->RemoveIdFromIdToIndexMaps(id());
-    layer_tree_->property_trees()->needs_rebuild = true;
+    layer_tree_host_->property_trees()->RemoveIdFromIdToIndexMaps(id());
+    layer_tree_host_->property_trees()->needs_rebuild = true;
     layer_tree_->UnregisterLayer(this);
     if (inputs_.element_id) {
-      layer_tree_->animation_host()->UnregisterElement(inputs_.element_id,
-                                                       ElementListType::ACTIVE);
+      layer_tree_host_->animation_host()->UnregisterElement(
+          inputs_.element_id, ElementListType::ACTIVE);
       layer_tree_host_->RemoveFromElementMap(this);
     }
   }
   if (host) {
-    host->GetLayerTree()->property_trees()->needs_rebuild = true;
+    host->property_trees()->needs_rebuild = true;
     host->GetLayerTree()->RegisterLayer(this);
     if (inputs_.element_id) {
       host->AddToElementMap(this);
       host->animation_host()->RegisterElement(inputs_.element_id,
                                               ElementListType::ACTIVE);
     }
   }
 
   layer_tree_host_ = host;
   layer_tree_ = host ? host->GetLayerTree() : nullptr;
@@ skipping 22 matching lines @@
 void Layer::SetNeedsUpdate() {
   if (layer_tree_host_ && !ignore_set_needs_commit_)
     layer_tree_host_->SetNeedsUpdateLayers();
 }
 
 void Layer::SetNeedsCommit() {
   if (!layer_tree_host_)
     return;
 
   SetNeedsPushProperties();
-  layer_tree_->property_trees()->needs_rebuild = true;
+  layer_tree_host_->property_trees()->needs_rebuild = true;
 
   if (ignore_set_needs_commit_)
     return;
 
   layer_tree_host_->SetNeedsCommit();
 }
 
 void Layer::SetNeedsCommitNoRebuild() {
   if (!layer_tree_host_)
     return;
 
   SetNeedsPushProperties();
 
   if (ignore_set_needs_commit_)
     return;
 
   layer_tree_host_->SetNeedsCommit();
 }
 
 void Layer::SetNeedsFullTreeSync() {
-  if (!layer_tree_)
+  if (!layer_tree_host_)
     return;
 
-  layer_tree_->SetNeedsFullTreeSync();
+  layer_tree_host_->SetNeedsFullTreeSync();
 }
 
 void Layer::SetNextCommitWaitsForActivation() {
   if (!layer_tree_host_)
     return;
 
   layer_tree_host_->SetNextCommitWaitsForActivation();
 }
 
 void Layer::SetNeedsPushProperties() {
@@ skipping 19 matching lines @@
 
 void Layer::SetParent(Layer* layer) {
   DCHECK(!layer || !layer->HasAncestor(this));
 
   parent_ = layer;
   SetLayerTreeHost(parent_ ? parent_->layer_tree_host() : nullptr);
 
   if (!layer_tree_host_)
     return;
 
-  layer_tree_->property_trees()->needs_rebuild = true;
+  layer_tree_host_->property_trees()->needs_rebuild = true;
 }
 
 void Layer::AddChild(scoped_refptr<Layer> child) {
   InsertChild(child, inputs_.children.size());
 }
 
 void Layer::InsertChild(scoped_refptr<Layer> child, size_t index) {
   DCHECK(IsPropertyChangeAllowed());
   child->RemoveFromParent();
   AddDrawableDescendants(child->NumDescendantsThatDrawContent() +
@@ skipping 225 matching lines @@
   DCHECK_LE(opacity, 1.f);
 
   if (inputs_.opacity == opacity)
     return;
   // We need to force a property tree rebuild when opacity changes from 1 to a
   // non-1 value or vice-versa as render surfaces can change.
   bool force_rebuild = opacity == 1.f || inputs_.opacity == 1.f;
   inputs_.opacity = opacity;
   SetSubtreePropertyChanged();
   if (layer_tree_host_ && !force_rebuild) {
-    PropertyTrees* property_trees = layer_tree_->property_trees();
+    PropertyTrees* property_trees = layer_tree_host_->property_trees();
     auto effect_id_to_index = property_trees->effect_id_to_index_map.find(id());
     if (effect_id_to_index != property_trees->effect_id_to_index_map.end()) {
       EffectNode* node =
           property_trees->effect_tree.Node(effect_id_to_index->second);
       node->opacity = opacity;
       node->effect_changed = true;
       property_trees->effect_tree.set_needs_update(true);
       SetNeedsCommitNoRebuild();
       return;
     }
@@ skipping 83 matching lines @@
 void Layer::SetPosition(const gfx::PointF& position) {
   DCHECK(IsPropertyChangeAllowed());
   if (inputs_.position == position)
     return;
   inputs_.position = position;
 
   if (!layer_tree_host_)
     return;
 
   SetSubtreePropertyChanged();
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                        id())) {
     DCHECK_EQ(transform_tree_index(),
               property_trees->transform_id_to_index_map[id()]);
     TransformNode* transform_node =
         property_trees->transform_tree.Node(transform_tree_index());
     transform_node->update_post_local_transform(position, transform_origin());
     transform_node->needs_local_transform_update = true;
     transform_node->transform_changed = true;
-    layer_tree_->property_trees()->transform_tree.set_needs_update(true);
+    layer_tree_host_->property_trees()->transform_tree.set_needs_update(true);
     SetNeedsCommitNoRebuild();
     return;
   }
 
   SetNeedsCommit();
 }
 
 bool Layer::IsContainerForFixedPositionLayers() const {
   if (!inputs_.transform.IsIdentityOrTranslation())
     return true;
@@ skipping 17 matching lines @@
   }
 }
 
 void Layer::SetTransform(const gfx::Transform& transform) {
   DCHECK(IsPropertyChangeAllowed());
   if (inputs_.transform == transform)
     return;
 
   SetSubtreePropertyChanged();
   if (layer_tree_host_) {
-    PropertyTrees* property_trees = layer_tree_->property_trees();
+    PropertyTrees* property_trees = layer_tree_host_->property_trees();
     if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                          id())) {
       // We need to trigger a rebuild if we could have affected 2d axis
       // alignment. We'll check to see if transform and inputs_.transform
       // are axis
       // align with respect to one another.
       DCHECK_EQ(transform_tree_index(),
                 property_trees->transform_id_to_index_map[id()]);
       TransformNode* transform_node =
           property_trees->transform_tree.Node(transform_tree_index());
       bool preserves_2d_axis_alignment =
           Are2dAxisAligned(inputs_.transform, transform);
       transform_node->local = transform;
       transform_node->needs_local_transform_update = true;
       transform_node->transform_changed = true;
-      layer_tree_->property_trees()->transform_tree.set_needs_update(true);
+      layer_tree_host_->property_trees()->transform_tree.set_needs_update(true);
       if (preserves_2d_axis_alignment)
         SetNeedsCommitNoRebuild();
       else
         SetNeedsCommit();
       inputs_.transform = transform;
       return;
     }
   }
 
   inputs_.transform = transform;
 
   SetNeedsCommit();
 }
 
 void Layer::SetTransformOrigin(const gfx::Point3F& transform_origin) {
   DCHECK(IsPropertyChangeAllowed());
   if (inputs_.transform_origin == transform_origin)
     return;
   inputs_.transform_origin = transform_origin;
 
   if (!layer_tree_host_)
     return;
 
   SetSubtreePropertyChanged();
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                        id())) {
     DCHECK_EQ(transform_tree_index(),
               property_trees->transform_id_to_index_map[id()]);
     TransformNode* transform_node =
         property_trees->transform_tree.Node(transform_tree_index());
     transform_node->update_pre_local_transform(transform_origin);
     transform_node->update_post_local_transform(position(), transform_origin);
     transform_node->needs_local_transform_update = true;
     transform_node->transform_changed = true;
-    layer_tree_->property_trees()->transform_tree.set_needs_update(true);
+    layer_tree_host_->property_trees()->transform_tree.set_needs_update(true);
     SetNeedsCommitNoRebuild();
     return;
   }
 
   SetNeedsCommit();
 }
 
 bool Layer::ScrollOffsetAnimationWasInterrupted() const {
   return GetAnimationHost()->ScrollOffsetAnimationWasInterrupted(element_id());
 }
@@ skipping 40 matching lines @@
 
   if (inputs_.clip_parent)
     inputs_.clip_parent->RemoveClipChild(this);
 
   inputs_.clip_parent = ancestor;
 
   if (inputs_.clip_parent)
     inputs_.clip_parent->AddClipChild(this);
 
   SetNeedsCommit();
-  if (layer_tree_)
-    layer_tree_->SetNeedsMetaInfoRecomputation(true);
+  if (layer_tree_host_)
+    layer_tree_host_->SetNeedsMetaInfoRecomputation(true);
 }
 
 void Layer::AddClipChild(Layer* child) {
   if (!clip_children_)
     clip_children_.reset(new std::set<Layer*>);
   clip_children_->insert(child);
   SetNeedsCommit();
 }
 
 void Layer::RemoveClipChild(Layer* child) {
   clip_children_->erase(child);
   if (clip_children_->empty())
     clip_children_ = nullptr;
   SetNeedsCommit();
 }
 
 void Layer::SetScrollOffset(const gfx::ScrollOffset& scroll_offset) {
   DCHECK(IsPropertyChangeAllowed());
 
   if (inputs_.scroll_offset == scroll_offset)
     return;
   inputs_.scroll_offset = scroll_offset;
 
   if (!layer_tree_host_)
     return;
 
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (scroll_tree_index() != ScrollTree::kInvalidNodeId && scrollable())
     property_trees->scroll_tree.SetScrollOffset(id(), scroll_offset);
 
   if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                        id())) {
     DCHECK_EQ(transform_tree_index(),
               property_trees->transform_id_to_index_map[id()]);
     TransformNode* transform_node =
         property_trees->transform_tree.Node(transform_tree_index());
     transform_node->scroll_offset = CurrentScrollOffset();
@@ skipping 12 matching lines @@
   // This function only gets called during a BeginMainFrame, so there
   // is no need to call SetNeedsUpdate here.
   DCHECK(layer_tree_host_ && layer_tree_host_->CommitRequested());
   if (inputs_.scroll_offset == scroll_offset)
     return;
   inputs_.scroll_offset = scroll_offset;
   SetNeedsPushProperties();
 
   bool needs_rebuild = true;
 
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (scroll_tree_index() != ScrollTree::kInvalidNodeId && scrollable())
     property_trees->scroll_tree.SetScrollOffset(id(), scroll_offset);
 
   if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                        id())) {
     DCHECK_EQ(transform_tree_index(),
               property_trees->transform_id_to_index_map[id()]);
     TransformNode* transform_node =
         property_trees->transform_tree.Node(transform_tree_index());
     transform_node->scroll_offset = CurrentScrollOffset();
@@ skipping 105 matching lines @@
 void Layer::SetTransformTreeIndex(int index) {
   DCHECK(IsPropertyChangeAllowed());
   if (transform_tree_index_ == index)
     return;
   transform_tree_index_ = index;
   SetNeedsPushProperties();
 }
 
 int Layer::transform_tree_index() const {
   if (!layer_tree_host_ ||
-      layer_tree_->property_trees()->sequence_number !=
+      layer_tree_host_->property_trees()->sequence_number !=
           property_tree_sequence_number_) {
     return TransformTree::kInvalidNodeId;
   }
   return transform_tree_index_;
 }
 
 void Layer::SetClipTreeIndex(int index) {
   DCHECK(IsPropertyChangeAllowed());
   if (clip_tree_index_ == index)
     return;
   clip_tree_index_ = index;
   SetNeedsPushProperties();
 }
 
 int Layer::clip_tree_index() const {
   if (!layer_tree_host_ ||
-      layer_tree_->property_trees()->sequence_number !=
+      layer_tree_host_->property_trees()->sequence_number !=
           property_tree_sequence_number_) {
     return ClipTree::kInvalidNodeId;
   }
   return clip_tree_index_;
 }
 
 void Layer::SetEffectTreeIndex(int index) {
   DCHECK(IsPropertyChangeAllowed());
   if (effect_tree_index_ == index)
     return;
   effect_tree_index_ = index;
   SetNeedsPushProperties();
 }
 
 int Layer::effect_tree_index() const {
   if (!layer_tree_host_ ||
-      layer_tree_->property_trees()->sequence_number !=
+      layer_tree_host_->property_trees()->sequence_number !=
           property_tree_sequence_number_) {
     return EffectTree::kInvalidNodeId;
   }
   return effect_tree_index_;
 }
 
 void Layer::SetScrollTreeIndex(int index) {
   DCHECK(IsPropertyChangeAllowed());
   if (scroll_tree_index_ == index)
     return;
   scroll_tree_index_ = index;
   SetNeedsPushProperties();
 }
 
 int Layer::scroll_tree_index() const {
   if (!layer_tree_host_ ||
-      layer_tree_->property_trees()->sequence_number !=
+      layer_tree_host_->property_trees()->sequence_number !=
           property_tree_sequence_number_) {
     return ScrollTree::kInvalidNodeId;
   }
   return scroll_tree_index_;
 }
 
 void Layer::InvalidatePropertyTreesIndices() {
   SetTransformTreeIndex(TransformTree::kInvalidNodeId);
   SetClipTreeIndex(ClipTree::kInvalidNodeId);
   SetEffectTreeIndex(EffectTree::kInvalidNodeId);
@@ skipping 162 matching lines @@
   layer->set_user_scrollable_horizontal(inputs_.user_scrollable_horizontal);
   layer->set_user_scrollable_vertical(inputs_.user_scrollable_vertical);
   layer->SetElementId(inputs_.element_id);
   layer->SetMutableProperties(inputs_.mutable_properties);
 
   // When a scroll offset animation is interrupted the new scroll position on
   // the pending tree will clobber any impl-side scrolling occuring on the
   // active tree. To do so, avoid scrolling the pending tree along with it
   // instead of trying to undo that scrolling later.
   if (ScrollOffsetAnimationWasInterrupted())
-    layer_tree_->property_trees()
+    layer_tree_host()
+        ->property_trees()
         ->scroll_tree.SetScrollOffsetClobberActiveValue(layer->id());
 
   // If the main thread commits multiple times before the impl thread actually
   // draws, then damage tracking will become incorrect if we simply clobber the
   // update_rect here. The LayerImpl's update_rect needs to accumulate (i.e.
   // union) any update changes that have occurred on the main thread.
   inputs_.update_rect.Union(layer->update_rect());
   layer->SetUpdateRect(inputs_.update_rect);
 
   layer->SetHasWillChangeTransformHint(has_will_change_transform_hint());
@@ skipping 89 matching lines @@
   DCHECK(!layer_tree_host_);
   DCHECK(inputs_.children.empty());
   DCHECK(!inputs_.mask_layer);
   DCHECK(!inputs_.replica_layer);
   DCHECK(layer_tree_host);
   DCHECK(proto.has_id());
 
   inputs_.layer_id = proto.id();
 
   layer_tree_host_ = layer_tree_host;
-  layer_tree_ = layer_tree_host->GetLayerTree();
+  layer_tree_ = layer_tree_host ? layer_tree_host->GetLayerTree() : nullptr;
   layer_tree_->RegisterLayer(this);
 
   for (int i = 0; i < proto.children_size(); ++i) {
     const proto::LayerNode& child_proto = proto.children(i);
     DCHECK(child_proto.has_type());
     scoped_refptr<Layer> child =
         LayerProtoConverter::FindOrAllocateAndConstruct(child_proto, layer_map);
     // The child must now refer to this layer as its parent, and must also have
     // the same LayerTreeHost. This must be done before deserializing children.
     DCHECK(!child->parent_);
@@ skipping 337 matching lines @@
   DCHECK_GE(opacity, 0.f);
   DCHECK_LE(opacity, 1.f);
 
   if (inputs_.opacity == opacity)
     return;
   inputs_.opacity = opacity;
   // Changing the opacity may make a previously hidden layer visible, so a new
   // recording may be needed.
   SetNeedsUpdate();
   if (layer_tree_host_) {
-    PropertyTrees* property_trees = layer_tree_->property_trees();
+    PropertyTrees* property_trees = layer_tree_host_->property_trees();
     if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::EFFECT,
                                          id())) {
       DCHECK_EQ(effect_tree_index(),
                 property_trees->effect_id_to_index_map[id()]);
       EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
       node->opacity = opacity;
       property_trees->effect_tree.set_needs_update(true);
     }
   }
 }
 
 void Layer::OnTransformAnimated(const gfx::Transform& transform) {
   if (inputs_.transform == transform)
     return;
   inputs_.transform = transform;
   // Changing the transform may change the visible part of this layer, so a new
   // recording may be needed.
   SetNeedsUpdate();
   if (layer_tree_host_) {
-    PropertyTrees* property_trees = layer_tree_->property_trees();
+    PropertyTrees* property_trees = layer_tree_host_->property_trees();
     if (property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                          id())) {
       DCHECK_EQ(transform_tree_index(),
                 property_trees->transform_id_to_index_map[id()]);
       TransformNode* node =
           property_trees->transform_tree.Node(transform_tree_index());
       node->local = transform;
       node->needs_local_transform_update = true;
       node->has_potential_animation = true;
       property_trees->transform_tree.set_needs_update(true);
     }
   }
 }
 
 void Layer::OnScrollOffsetAnimated(const gfx::ScrollOffset& scroll_offset) {
   // Do nothing. Scroll deltas will be sent from the compositor thread back
   // to the main thread in the same manner as during non-animated
   // compositor-driven scrolling.
 }
 
 void Layer::OnTransformIsCurrentlyAnimatingChanged(
     bool is_currently_animating) {
   DCHECK(layer_tree_host_);
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                         id()))
     return;
   DCHECK_EQ(transform_tree_index(),
             property_trees->transform_id_to_index_map[id()]);
   TransformNode* node =
       property_trees->transform_tree.Node(transform_tree_index());
   node->is_currently_animating = is_currently_animating;
 }
 
 void Layer::OnTransformIsPotentiallyAnimatingChanged(
     bool has_potential_animation) {
   if (!layer_tree_host_)
     return;
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::TRANSFORM,
                                         id()))
     return;
   DCHECK_EQ(transform_tree_index(),
             property_trees->transform_id_to_index_map[id()]);
   TransformNode* node =
       property_trees->transform_tree.Node(transform_tree_index());
 
   node->has_potential_animation = has_potential_animation;
   if (has_potential_animation) {
     node->has_only_translation_animations = HasOnlyTranslationTransforms();
   } else {
     node->has_only_translation_animations = true;
   }
   property_trees->transform_tree.set_needs_update(true);
 }
 
 void Layer::OnOpacityIsCurrentlyAnimatingChanged(bool is_currently_animating) {
   DCHECK(layer_tree_host_);
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::EFFECT, id()))
     return;
   DCHECK_EQ(effect_tree_index(), property_trees->effect_id_to_index_map[id()]);
   EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
   node->is_currently_animating_opacity = is_currently_animating;
 }
 
 void Layer::OnOpacityIsPotentiallyAnimatingChanged(
     bool has_potential_animation) {
   DCHECK(layer_tree_host_);
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::EFFECT, id()))
     return;
   DCHECK_EQ(effect_tree_index(), property_trees->effect_id_to_index_map[id()]);
   EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
   node->has_potential_opacity_animation =
       has_potential_animation || OpacityCanAnimateOnImplThread();
   property_trees->effect_tree.set_needs_update(true);
 }
 
 void Layer::OnFilterIsCurrentlyAnimatingChanged(bool is_currently_animating) {
   DCHECK(layer_tree_host_);
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::EFFECT, id()))
     return;
   DCHECK_EQ(effect_tree_index(), property_trees->effect_id_to_index_map[id()]);
   EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
   node->is_currently_animating_filter = is_currently_animating;
 }
 
 void Layer::OnFilterIsPotentiallyAnimatingChanged(
     bool has_potential_animation) {
   DCHECK(layer_tree_host_);
-  PropertyTrees* property_trees = layer_tree_->property_trees();
+  PropertyTrees* property_trees = layer_tree_host_->property_trees();
   if (!property_trees->IsInIdToIndexMap(PropertyTrees::TreeType::EFFECT, id()))
     return;
   DCHECK_EQ(effect_tree_index(), property_trees->effect_id_to_index_map[id()]);
   EffectNode* node = property_trees->effect_tree.Node(effect_tree_index());
   node->has_potential_filter_animation = has_potential_animation;
 }
 
 bool Layer::HasActiveAnimationForTesting() const {
   return layer_tree_host_
              ? GetAnimationHost()->HasActiveAnimationForTesting(element_id())
@@ skipping 91 matching lines @@
 
 void Layer::DidBeginTracing() {
   // We'll be dumping layer trees as part of trace, so make sure
   // PushPropertiesTo() propagates layer debug info to the impl
   // side -- otherwise this won't happen for the the layers that
   // remain unchanged since tracing started.
   SetNeedsPushProperties();
 }
 
 int Layer::num_copy_requests_in_target_subtree() {
-  return layer_tree_->property_trees()
+  return layer_tree_host()
+      ->property_trees()
       ->effect_tree.Node(effect_tree_index())
       ->num_copy_requests_in_subtree;
 }
 
 gfx::Transform Layer::screen_space_transform() const {
   DCHECK_NE(transform_tree_index_, TransformTree::kInvalidNodeId);
   return draw_property_utils::ScreenSpaceTransform(
-      this, layer_tree_->property_trees()->transform_tree);
+      this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 LayerTree* Layer::GetLayerTree() const {
   return layer_tree_;
 }
 
 }  // namespace cc