cc : Add layer_list to LayerTreeImpl and build it for tests

cc/trees/layer_tree_impl.h

 // Copyright 2012 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_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 250 matching lines @@
     return top_controls_shown_ratio_.get();
   }
   const SyncedTopControls* top_controls_shown_ratio() const {
     return top_controls_shown_ratio_.get();
   }
 
   // Updates draw properties and render surface layer list, as well as tile
   // priorities. Returns false if it was unable to update.  Updating lcd
   // text may cause invalidations, so should only be done after a commit.
   bool UpdateDrawProperties(bool update_lcd_text);
-  void BuildPropertyTreesForTesting();
+  void BuildLayerListAndPropertyTreesForTesting();
 
   void set_needs_update_draw_properties() {
     needs_update_draw_properties_ = true;
   }
   bool needs_update_draw_properties() const {
     return needs_update_draw_properties_;
   }
 
   bool is_in_resourceless_software_draw_mode() {
     return (layer_tree_host_impl_->GetDrawMode() ==
@@ skipping 230 matching lines @@
   float min_page_scale_factor_;
   float max_page_scale_factor_;
 
   float device_scale_factor_;
   float painted_device_scale_factor_;
 
   scoped_refptr<SyncedElasticOverscroll> elastic_overscroll_;
 
   std::unique_ptr<OwnedLayerImplList> layers_;
   LayerImplMap layer_id_map_;
+  std::vector<LayerImpl*> layer_list_;
   // Set of layers that need to push properties.
   std::unordered_set<LayerImpl*> layers_that_should_push_properties_;
 
   std::unordered_map<uint64_t, ElementLayers> element_layers_map_;
 
   std::unordered_map<int, float> opacity_animations_map_;
   std::unordered_map<int, gfx::Transform> transform_animations_map_;
 
   // Maps from clip layer ids to scroll layer ids.  Note that this only includes
   // the subset of clip layers that act as scrolling containers.  (This is
@@ skipping 40 matching lines @@
   bool top_controls_shrink_blink_size_;
   float top_controls_height_;
 
   // The amount that the top controls are shown from 0 (hidden) to 1 (fully
   // shown).
   scoped_refptr<SyncedTopControls> top_controls_shown_ratio_;
 
   std::unique_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
  private:
+  void BuildLayerListForTesting();
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_