Add ScrollTree builder and unit test

cc/trees/property_tree.cc

 // 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.
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
 
 #include "base/logging.h"
@@ skipping 453 matching lines @@
   is_drawn = data.is_drawn();
   screen_space_opacity_is_animating = data.screen_space_opacity_is_animating();
   num_copy_requests_in_subtree = data.num_copy_requests_in_subtree();
   transform_id = data.transform_id();
   clip_id = data.clip_id();
 }
 
 ScrollNodeData::ScrollNodeData()
     : scrollable(false),
       should_scroll_on_main_thread(false),
-      scroll_blocks_on(ScrollBlocksOn::SCROLL_BLOCKS_ON_NONE),
       contains_non_fast_scrollable_region(false),
       transform_id(0) {}
 
 bool ScrollNodeData::operator==(const ScrollNodeData& other) const {
   return scrollable == other.scrollable &&
          should_scroll_on_main_thread == other.should_scroll_on_main_thread &&
-         scroll_blocks_on == other.scroll_blocks_on &&
          contains_non_fast_scrollable_region ==
              other.contains_non_fast_scrollable_region &&
          transform_id == other.transform_id;
 }
 
 void ScrollNodeData::ToProtobuf(proto::TreeNode* proto) const {
   DCHECK(!proto->has_scroll_node_data());
   proto::ScrollNodeData* data = proto->mutable_scroll_node_data();
   data->set_scrollable(scrollable);
   data->set_should_scroll_on_main_thread(should_scroll_on_main_thread);
-  data->set_scroll_blocks_on(scroll_blocks_on);
   data->set_contains_non_fast_scrollable_region(
       contains_non_fast_scrollable_region);
   data->set_transform_id(transform_id);
 }
 
 void ScrollNodeData::FromProtobuf(const proto::TreeNode& proto) {
   DCHECK(proto.has_scroll_node_data());
   const proto::ScrollNodeData& data = proto.scroll_node_data();
 
   scrollable = data.scrollable();
   should_scroll_on_main_thread = data.should_scroll_on_main_thread();
-  scroll_blocks_on = (ScrollBlocksOn)data.scroll_blocks_on();
   contains_non_fast_scrollable_region =
       data.contains_non_fast_scrollable_region();
   transform_id = data.transform_id();
 }
 
 void TransformTree::clear() {
   PropertyTree<TransformNode>::clear();
 
   nodes_affected_by_inner_viewport_bounds_delta_.clear();
   nodes_affected_by_outer_viewport_bounds_delta_.clear();
@@ skipping 746 matching lines @@
   effect_tree.FromProtobuf(proto.effect_tree());
   clip_tree.FromProtobuf(proto.clip_tree());
   scroll_tree.FromProtobuf(proto.scroll_tree());
 
   needs_rebuild = proto.needs_rebuild();
   non_root_surfaces_enabled = proto.non_root_surfaces_enabled();
   sequence_number = proto.sequence_number();
 }
 
 }  // namespace cc