remove the function is_on_road(box).

* The function has no use case.
* The function is misleading.

modules/map/pnc_map/path.cc

@@ -546,17 +546,6 @@ bool Path::is_on_path(const Vec2d& point) const {
   return false;
 }
 
-bool Path::is_on_path(const Box2d& box) const {
-  std::vector<Vec2d> corners;
-  box.GetAllCorners(&corners);
-  for (const auto& corner : corners) {
-    if (!is_on_path(corner)) {
-      return false;
-    }
-  }
-  return true;
-}
-
 bool Path::overlap_with(const common::math::Box2d& box, double width) const {
   if (_use_path_approximation) {
     return _approximation.overlap_with(*this, box, width);

modules/map/pnc_map/path.h

@@ -261,8 +261,6 @@ class Path {
   bool get_width(const double s, double* left_width, double* right_width) const;
 
   bool is_on_path(const common::math::Vec2d& point) const;
-  // requires all corners of the box on path.
-  bool is_on_path(const common::math::Box2d& box) const;
   bool overlap_with(const common::math::Box2d& box, double width) const;
 
   std::string debug_string() const;