cc : Move LayerImpl::children to test properties

cc/layers/layer_impl_test_properties.h

 // Copyright 2016 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_LAYERS_LAYER_IMPL_TEST_PROPERTIES_H_
 #define CC_LAYERS_LAYER_IMPL_TEST_PROPERTIES_H_
 
 #include <set>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
+#include "cc/layers/layer_collections.h"
 #include "cc/layers/layer_position_constraint.h"
 #include "ui/gfx/geometry/point3_f.h"
 
 namespace cc {
 
 class CopyOutputRequest;
 class LayerImpl;
 
 struct CC_EXPORT LayerImplTestProperties {
   LayerImplTestProperties();
   ~LayerImplTestProperties();
 
   bool double_sided;
   bool force_render_surface;
   bool is_container_for_fixed_position_layers;
   bool should_flatten_transform;
   bool hide_layer_and_subtree;
   bool opacity_can_animate;
   int num_descendants_that_draw_content;
   size_t num_unclipped_descendants;
   float opacity;
   LayerPositionConstraint position_constraint;
   gfx::Point3F transform_origin;
   LayerImpl* scroll_parent;
   std::unique_ptr<std::set<LayerImpl*>> scroll_children;
   LayerImpl* clip_parent;
   std::unique_ptr<std::set<LayerImpl*>> clip_children;
   std::vector<std::unique_ptr<CopyOutputRequest>> copy_requests;
+  LayerImplList children;
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_TEST_PROPERTIES_H_