Remove dead code in AppListItem

Most likely a leftover from when ChromeAppListItem was created.

Bug: none
Test: compile
Change-Id: I238d57363086d300f00ed4c815396a3160f6f55a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1687101
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Auto-Submit: Vladislav Kaznacheev <kaznacheev@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#674529}
4 files changed