Update from https://crrev.com/320343

cc/trees/layer_sorter.h

-// Copyright 2011 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_LAYER_SORTER_H_
-#define CC_TREES_LAYER_SORTER_H_
-
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/containers/hash_tables.h"
-#include "cc/base/cc_export.h"
-#include "cc/layers/layer_impl.h"
-#include "ui/gfx/geometry/point3_f.h"
-#include "ui/gfx/geometry/quad_f.h"
-#include "ui/gfx/geometry/rect_f.h"
-#include "ui/gfx/geometry/vector3d_f.h"
-
-namespace gfx {
-class Transform;
-}
-
-namespace cc {
-struct GraphEdge;
-
-// Holds various useful properties derived from a layer's 3D outline.
-struct CC_EXPORT LayerShape {
-  LayerShape();
-  LayerShape(float width, float height, const gfx::Transform& draw_transform);
-  ~LayerShape();
-
-  float LayerZFromProjectedPoint(const gfx::PointF& p) const;
-
-  gfx::Vector3dF layer_normal;
-  gfx::Point3F transform_origin;
-  gfx::QuadF projected_quad;
-  gfx::RectF projected_bounds;
-};
-
-struct GraphNode {
-  explicit GraphNode(LayerImpl* layer_impl);
-  ~GraphNode();
-
-  LayerImpl* layer;
-  LayerShape shape;
-  std::vector<GraphEdge*> incoming;
-  std::vector<GraphEdge*> outgoing;
-  float incoming_edge_weight;
-};
-
-struct GraphEdge {
-  GraphEdge(GraphNode* from_node, GraphNode* to_node, float weight)
-      : from(from_node),
-        to(to_node),
-        weight(weight) {}
-
-  GraphNode* from;
-  GraphNode* to;
-  float weight;
-};
-
-
-
-class CC_EXPORT LayerSorter {
- public:
-  LayerSorter();
-  ~LayerSorter();
-
-  void Sort(LayerImplList::iterator first, LayerImplList::iterator last);
-
-  enum ABCompareResult { A_BEFORE_B, B_BEFORE_A, NONE };
-
-  static ABCompareResult CheckOverlap(LayerShape* a,
-                                      LayerShape* b,
-                                      float z_threshold,
-                                      float* weight);
-
- private:
-  typedef std::vector<GraphNode> NodeList;
-  typedef std::vector<GraphEdge> EdgeList;
-  NodeList nodes_;
-  EdgeList edges_;
-  float z_range_;
-
-  typedef base::hash_map<GraphEdge*, GraphEdge*> EdgeMap;
-  EdgeMap active_edges_;
-
-  void CreateGraphNodes(LayerImplList::iterator first,
-                        LayerImplList::iterator last);
-  void CreateGraphEdges();
-  void RemoveEdgeFromList(GraphEdge* graph, std::vector<GraphEdge*>* list);
-
-  DISALLOW_COPY_AND_ASSIGN(LayerSorter);
-};
-
-}  // namespace cc
-#endif  // CC_TREES_LAYER_SORTER_H_