How to reproduce:
1. Turn on `desktop-save-mode`
2. dired some directory
3. Press `(` to turn on `dired-hide-details-mode`
4. C-x C-c, when asked to save desktop, choose yes
5. Launch emacs again, desktop restored the dired buffer but not
`dired-hide-details-mode`

What went wrong:
`dired-hide-details-mode`'s definition does not declare a lighter or a
keymap, thus it is not added to `minor-mode-alist` by
`define-minor-mode`. So when `desktop` tries to get the buffer's info to
save to `.emacs.desktop` via `desktop-buffer-info`,
`dired-hide-details-mode` does not exist, and thus not saved to the
session file.

Fix:
Just declare an empty lighter. I've attached a patch for this.