[#4] Pass gfx structs by const ref (gfx::PointF)

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"
@@ skipping 24 matching lines @@
 
 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(gfx::PointF p) const;
+  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();
@@ skipping 49 matching lines @@
   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_