cc:: Add transform nodes at boundaries of 3d rendering contexts

cc/trees/property_tree.h

 // Copyright 2014 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_PROPERTY_TREE_H_
 #define CC_TREES_PROPERTY_TREE_H_
 
 #include <stddef.h>
 
 #include <vector>
@@ skipping 74 matching lines @@
   // This id is used for all content that draws into a render surface associated
   // with this transform node.
   int content_target_id;
 
   // This is the node with respect to which source_offset is defined. This will
   // not be needed once layerization moves to cc, but is needed in order to
   // efficiently update the transform tree for changes to position in the layer
   // tree.
   int source_node_id;
 
+  // This id determines which 3d rendering context the node is in. 0 is a
+  // special value and indicates that the node is not in any 3d rendering
+  // context.
+  int sorting_context_id;
+
   // TODO(vollick): will be moved when accelerated effects are implemented.
   bool needs_local_transform_update : 1;
 
   bool is_invertible : 1;
   bool ancestors_are_invertible : 1;
 
   bool is_animated : 1;
   bool to_screen_is_animated : 1;
   bool has_only_translation_animations : 1;
   bool to_screen_has_scale_animation : 1;
@@ skipping 431 matching lines @@
   ClipTree clip_tree;
   ScrollTree scroll_tree;
   bool needs_rebuild;
   bool non_root_surfaces_enabled;
   int sequence_number;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_