Fix group divider make chrome crash issue.

ListMenuItemView's group divider is only existed in
popup_menu_item_layout, but Chrome use list_menu_item_layout.
It will make NullPointerException and crash the chrome.
Fix it by check null before using the group divider.

Bug: 66987086
Test: Long click an image from webpage in chrome, click the "Download
image" item, and it works well.

Change-Id: Ie5f19194a968b4fff0126e1cf8bebda5344c8105