Planning: more changes in st_boundarry_mapper. extract common code to functions.

modules/planning/common/path_obstacle.h

@@ -78,7 +78,8 @@ class PathObstacle {
   std::vector<ObjectDecisionType> decisions_;
   std::vector<std::string> decider_tags_;
   SLBoundary sl_boundary_;
-  StGraphBoundary st_boundary_;
+  // TODO: add st_boundary_ here.
+  // StGraphBoundary st_boundary_;
 };
 
 }  // namespace planning

modules/planning/optimizer/st_graph/st_graph_boundary.h

@@ -55,7 +55,8 @@ class StGraphBoundary : public common::math::Polygon2d {
 
   ~StGraphBoundary() = default;
 
-  bool IsEmpty() const { return points.empty(); }
+  // TODO: add this function.
+  // bool IsEmpty() const { return points.empty(); }
   bool IsPointInBoundary(const StGraphPoint& st_graph_point) const;
   bool IsPointInBoundary(const STPoint& st_point) const;