Download .crx file from web server, and don't let chrome display yellow bar at the top of the page

download_crx.go

package main

import (
	"log"
	"net/http"
	"os"
	"strconv"
)

func handler(w http.ResponseWriter, r *http.Request) {
	file_name := r.URL.Path[1:]
	log.Println(file_name)
	if len(file_name) == 0 {
		log.Println("file_name is empty")
		return
	}

	file, err := os.Open(file_name)
	if err != nil {
		log.Println("Unable to open file", file_name)
		return
	}
	defer file.Close()

	stat, err := file.Stat()
	if err != nil {
		log.Println("Unable to get file size")
		return
	}

	file_size := stat.Size()
	bs := make([]byte, file_size)
	_, err = file.Read(bs)
	if err != nil {
		log.Println("Unable to read file")
		return
	}

	w.Header().Set("Content-Type", "application/force-download")
	w.Header().Set("Content-Transfer-Encoding", "BINARY")
	w.Header().Set("Content-Disposition", "attachment; filename=\""+file_name+"\"")
	w.Header().Set("Content-length", strconv.Itoa(int(file_size)))
	w.Header().Set("Pragma", "no-cache")
	w.Write(bs)
}

func main() {
	http.HandleFunc("/", handler)
	err := http.ListenAndServe(":80", nil)
	if err != nil {
		log.Fatal(err)
	}
}