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..c38778bb26dbdf55a70064173af029f2baa1ccfb 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -378,7 +378,8 @@ class CC_EXPORT PropertyTree {
   int next_available_id() const { return static_cast<int>(size()); }
 
   void ToProtobuf(proto::PropertyTree* proto) const;
-  void FromProtobuf(const proto::PropertyTree& proto);
+  void FromProtobuf(const proto::PropertyTree& proto,
+                    std::unordered_map<int, int>* node_id_to_index_map);
 
   void SetPropertyTrees(PropertyTrees* property_trees) {
     property_trees_ = property_trees;
@@ -505,7 +506,8 @@ class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
   gfx::Transform ToScreenSpaceTransformWithoutSublayerScale(int id) const;
 
   void ToProtobuf(proto::PropertyTree* proto) const;
-  void FromProtobuf(const proto::PropertyTree& proto);
+  void FromProtobuf(const proto::PropertyTree& proto,
+                    std::unordered_map<int, int>* node_id_to_index_map);
 
  private:
   // Returns true iff the node at |desc_id| is a descendant of the node at
@@ -561,7 +563,8 @@ class CC_EXPORT ClipTree final : public PropertyTree<ClipNode> {
   gfx::RectF ViewportClip();
 
   void ToProtobuf(proto::PropertyTree* proto) const;
-  void FromProtobuf(const proto::PropertyTree& proto);
+  void FromProtobuf(const proto::PropertyTree& proto,
+                    std::unordered_map<int, int>* node_id_to_index_map);
 };
 
 class CC_EXPORT EffectTree final : public PropertyTree<EffectNode> {
@@ -581,7 +584,8 @@ class CC_EXPORT EffectTree final : public PropertyTree<EffectNode> {
   void ResetChangeTracking();
 
   void ToProtobuf(proto::PropertyTree* proto) const;
-  void FromProtobuf(const proto::PropertyTree& proto);
+  void FromProtobuf(const proto::PropertyTree& proto,
+                    std::unordered_map<int, int>* node_id_to_index_map);
 
  private:
   void UpdateOpacities(EffectNode* node, EffectNode* parent_node);
@@ -599,7 +603,8 @@ class CC_EXPORT ScrollTree final : public PropertyTree<ScrollNode> {
   bool operator==(const ScrollTree& other) const;
 
   void ToProtobuf(proto::PropertyTree* proto) const;
-  void FromProtobuf(const proto::PropertyTree& proto);
+  void FromProtobuf(const proto::PropertyTree& proto,
+                    std::unordered_map<int, int>* node_id_to_index_map);
 
   void clear();
 
@@ -665,6 +670,10 @@ class CC_EXPORT PropertyTrees final {
   void ToProtobuf(proto::PropertyTrees* proto) const;
   void FromProtobuf(const proto::PropertyTrees& proto);
 
+  std::unordered_map<int, int> transform_id_to_index_map;
+  std::unordered_map<int, int> effect_id_to_index_map;
+  std::unordered_map<int, int> clip_id_to_index_map;
+  std::unordered_map<int, int> scroll_id_to_index_map;
   TransformTree transform_tree;
   EffectTree effect_tree;
   ClipTree clip_tree;