cc: Construct the RSLL without using layer hierarchy

cc/layers/render_surface_impl.h

 // Copyright 2011 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.
 
 #ifndef CC_LAYERS_RENDER_SURFACE_IMPL_H_
 #define CC_LAYERS_RENDER_SURFACE_IMPL_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 37 matching lines @@
 
   // Returns the rect that encloses the RenderSurfaceImpl including any
   // reflection.
   gfx::RectF DrawableContentRect() const;
 
   void SetDrawOpacity(float opacity) {
     draw_properties_.draw_opacity = opacity;
   }
   float draw_opacity() const { return draw_properties_.draw_opacity; }
 
-  void SetNearestOcclusionImmuneAncestor(RenderSurfaceImpl* surface) {
+  void SetNearestOcclusionImmuneAncestor(const RenderSurfaceImpl* surface) {
     nearest_occlusion_immune_ancestor_ = surface;
   }
   const RenderSurfaceImpl* nearest_occlusion_immune_ancestor() const {
     return nearest_occlusion_immune_ancestor_;
   }
 
   SkColor GetDebugBorderColor() const;
   SkColor GetReplicaDebugBorderColor() const;
 
   float GetDebugBorderWidth() const;
@@ skipping 135 matching lines @@
   gfx::Rect accumulated_content_rect_;
   bool surface_property_changed_ : 1;
 
   bool contributes_to_drawn_surface_ : 1;
 
   LayerImplList layer_list_;
   Occlusion occlusion_in_content_space_;
 
   // The nearest ancestor target surface that will contain the contents of this
   // surface, and that ignores outside occlusion. This can point to itself.
-  RenderSurfaceImpl* nearest_occlusion_immune_ancestor_;
+  const RenderSurfaceImpl* nearest_occlusion_immune_ancestor_;
 
   std::unique_ptr<DamageTracker> damage_tracker_;
 
   // For LayerIteratorActions
   int target_render_surface_layer_index_history_;
   size_t current_layer_index_history_;
 
   friend class LayerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(RenderSurfaceImpl);
 };
 
 }  // namespace cc
 #endif  // CC_LAYERS_RENDER_SURFACE_IMPL_H_