Add Scroll Tree data structure

cc/proto/property_tree.proto

 // Copyright 2015 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.
 
 syntax = "proto2";
 
 import "rectf.proto";
 import "scroll_offset.proto";
 import "transform.proto";
 import "vector2df.proto";
@@ skipping 68 matching lines @@
 // Proto for struct EffectNodeData.
 message EffectNodeData {
   optional float opacity = 1;
   optional float screen_space_opacity = 2;
   optional bool has_render_surface = 3;
   optional int64 num_copy_requests_in_subtree = 4;
   optional int64 transform_id = 5;
   optional int64 clip_id = 6;
 }
 
+message ScrollNodeData {
+  optional bool scrollable = 1;
+  optional bool should_scroll_on_main_thread = 2;
+  optional int32 scroll_blocks_on = 3;
+  optional bool contains_non_fast_scrollable_region = 4;
+  optional int64 transform_id = 5;
+}
+
 // This defines the proto used for all types of struct TreeNode.
 message TreeNode {
   // The following fields are the base TreeNode properties. This list
   // corresponds to the data members from struct TreeNode.
   optional int64 id = 1;
   optional int64 parent_id = 2;
   optional int64 owner_id = 3;
 
   // The following fields correspond to the possible values for TreeNode::data.
   // Only one of these fields should be set, based on the type of property tree
   // this node belongs to.
   optional TranformNodeData transform_node_data = 1000;
   optional ClipNodeData clip_node_data = 1001;
   optional EffectNodeData effect_node_data = 1002;
+  optional ScrollNodeData scroll_node_data = 1003;
 }
 
 // This defines the proto used for all property trees. PropertyType denotes the
 // type of this tree.
 message PropertyTree {
   enum PropertyType {
     Transform = 1;
     Clip = 2;
     Effect = 3;
+    Scroll = 4;
   }
 
   // The following fields are the base PropertyTree properties. This list
   // corresponds to the data members from class PropertyTree.
   optional PropertyType property_type = 1;
   repeated TreeNode nodes = 2;
   optional bool needs_update = 3;
 
   // The following fields denote the data members for each subclass of
   // PropertyTree. Only one of these fields should be set, depending on the type
@@ skipping 13 matching lines @@
       [packed = true];
   repeated int64 nodes_affected_by_outer_viewport_bounds_delta = 8
       [packed = true];
 }
 
 // Proto for class PropertyTrees.
 message PropertyTrees {
   optional PropertyTree transform_tree = 1;
   optional PropertyTree effect_tree = 2;
   optional PropertyTree clip_tree = 3;
+  optional PropertyTree scroll_tree = 4;
 
-  optional bool needs_rebuild = 4;
-  optional bool non_root_surfaces_enabled = 5;
-  optional int64 sequence_number = 6;
+  optional bool needs_rebuild = 5;
+  optional bool non_root_surfaces_enabled = 6;
+  optional int64 sequence_number = 7;
 }