Company 2

(defun tab-indent-or-complete ()
  (interactive)
  (if (minibufferp)
      (minibuffer-complete)
    (if (or (not yas-minor-mode)
            (null (do-yas-expand)))
        (if (check-expansion)
            (company-complete-common)
          (indent-for-tab-command)))))

(global-set-key [backtab] 'tab-indent-or-complete)