cc: Make LayerTreeHost a protected Layer member.

cc/trees/layer_tree.cc

Index: cc/trees/layer_tree.cc
diff --git a/cc/trees/layer_tree.cc b/cc/trees/layer_tree.cc
index cf0c3bc4760acdc50ee11f53511f2f8162d980bf..72460a4154e671886ea592e6b1ce2e3e785e6d53 100644
--- a/cc/trees/layer_tree.cc
+++ b/cc/trees/layer_tree.cc
@@ -17,6 +17,7 @@
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_host_common.h"
 #include "cc/trees/layer_tree_impl.h"
+#include "cc/trees/property_tree_builder.h"
 
 namespace cc {
 
@@ -325,6 +326,10 @@ void LayerTree::SetNeedsCommit() {
   layer_tree_host_->SetNeedsCommit();
 }
 
+const LayerTreeSettings& LayerTree::GetSettings() const {
+  return layer_tree_host_->GetSettings();
+}
+
 void LayerTree::SetPropertyTreesNeedRebuild() {
   property_trees_.needs_rebuild = true;
   layer_tree_host_->SetNeedsUpdateLayers();
@@ -581,6 +586,16 @@ void LayerTree::SetElementIdsForTesting() {
   LayerTreeHostCommon::CallFunctionForEveryLayer(this, SetElementIdForTesting);
 }
 
+void LayerTree::BuildPropertyTreesForTesting() {
+  PropertyTreeBuilder::PreCalculateMetaInformation(root_layer());
+  gfx::Transform identity_transform;
+  PropertyTreeBuilder::BuildPropertyTrees(
+      root_layer(), page_scale_layer(), inner_viewport_scroll_layer(),
+      outer_viewport_scroll_layer(), overscroll_elasticity_layer(),
+      elastic_overscroll(), page_scale_factor(), device_scale_factor(),
+      gfx::Rect(device_viewport_size()), identity_transform, property_trees());
+}
+
 bool LayerTree::IsElementInList(ElementId element_id,
                                 ElementListType list_type) const {
   return list_type == ElementListType::ACTIVE && LayerByElementId(element_id);