cc : Add LayerToPropertyTreeIndices map to PropertyTrees

cc/trees/property_tree.h

Index: cc/trees/property_tree.h
diff --git a/cc/trees/property_tree.h b/cc/trees/property_tree.h
index 002bea1a37cd96105e6b5805d7c8bd326fe1f12f..edcbb15a613dbca001f3bc37e267751f134ac3ed 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -665,6 +665,10 @@ class CC_EXPORT PropertyTrees final {
   void ToProtobuf(proto::PropertyTrees* proto) const;
   void FromProtobuf(const proto::PropertyTrees& proto);
 
+  std::unordered_map<int, int> transform_node_owner_to_node_map;
+  std::unordered_map<int, int> effect_node_owner_to_node_map;
+  std::unordered_map<int, int> clip_node_owner_to_node_map;
+  std::unordered_map<int, int> scroll_node_owner_to_node_map;

[ajuma, 2016/05/13 14:38:53]

Nit: how about using names like "transform_id_to_index_map" so they continue to
make sense for trees built by Blink (where nodes won't have an 'owner')?

[jaydasika, 2016/05/13 19:40:39]

Done.

   TransformTree transform_tree;
   EffectTree effect_tree;
   ClipTree clip_tree;