PnC: add a field of lane_id in path_point proto

modules/common/proto/pnc_point.proto

@@ -44,6 +44,8 @@ message PathPoint {
   optional double dkappa = 7;
   // derivative of derivative of kappa w.r.t s.
   optional double ddkappa = 8;
+  // The lane ID where the path point is on
+  optional string lane_id = 9;
 }
 
 message Path {

modules/prediction/common/prediction_util.cc

@@ -201,6 +201,7 @@ void GenerateLaneSequenceTrajectoryPoints(
     path_point.set_y(point.y());
     path_point.set_z(0.0);
     path_point.set_theta(theta);
+    path_point.set_lane_id(lane_id);
     trajectory_point.mutable_path_point()->CopyFrom(path_point);
     trajectory_point.set_v(lane_speed);
     trajectory_point.set_a(lane_acc);

modules/prediction/predictor/move_sequence/move_sequence_predictor.cc

@@ -134,8 +134,6 @@ void MoveSequencePredictor::Predict(Obstacle* obstacle) {
            << "] will draw a lane sequence trajectory [" << ToString(sequence)
            << "] with probability [" << sequence.probability() << "].";
 
-    // TODO(Prediction): remove the following line
-    // std::string curr_lane_id = sequence.lane_segment(0).lane_id();
     std::vector<TrajectoryPoint> points;
     DrawMoveSequenceTrajectoryPoints(*obstacle, sequence,
                                      FLAGS_prediction_duration,
@@ -275,6 +273,7 @@ void MoveSequencePredictor::DrawManeuverTrajectoryPoints(
     path_point.set_y(point.y());
     path_point.set_z(0.0);
     path_point.set_theta(theta);
+    path_point.set_lane_id(lane_id);
     trajectory_point.mutable_path_point()->CopyFrom(path_point);
     trajectory_point.set_v(lane_speed);
     trajectory_point.set_a(lane_acc);