opens url in chromium if no browser is opened. reuse opened browser if already opened

open-browser.el

(defun is-proc-opened (procname)
  (let ((procs (list-system-processes)))
    (remove-if-not (lambda (proc)
		     (search procname
			     (name-of-proccess proc)))
		   procs)))

(defun name-of-process (proc)
  (cdr (car (process-attributes proc))))

(defun browse-url-open-browser (url &rest new-window)
  (setq browse-url-generic-program (open-browser))
  (apply 'browse-url-generic url new-window))

(defun open-browser ()
  "define the priorities of browsers"
  (if (is-proc-opened "chromium")
      "chromium-browser"
    (if (is-proc-opened "firefox")
	"firefox"
      "chromium-browser")))

(setq browse-url-browser-function 'browse-url-open-browser)