Introduce Property Trees

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index b9dd3c95516b87ec54d896603bff1b3b4169be74..a5e07dad98326152fbcbbbf6a444721c2ffa7aca 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -469,9 +469,9 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   // The tree index is slightly counter-intuitive. If |this| is in the transform
   // tree, then the index corresponds to this layer's spot in the tree.
   // Otherwise, the it is the index of our transform parent.
-  void set_transform_tree_index(size_t index) { transform_tree_index_ = index; }
-  void set_opacity_tree_index(size_t index) { opacity_tree_index_ = index; }
-  void set_clip_tree_index(size_t index) { clip_tree_index_ = index; }
+  void set_transform_tree_index(int index) { transform_tree_index_ = index; }
+  void set_opacity_tree_index(int index) { opacity_tree_index_ = index; }
+  void set_clip_tree_index(int index) { clip_tree_index_ = index; }
   int clip_tree_index() const { return clip_tree_index_; }
   int transform_tree_index() const { return transform_tree_index_; }
   int opacity_tree_index() const { return opacity_tree_index_; }
@@ -483,6 +483,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
     return offset_to_transform_parent_;
   }
 
+  // TODO(vollick): Nuke.
   void set_fixed_position_container(Layer* layer) {
     fixed_position_container_ = layer;
   }