Add 'New' badge to 'Add tab to new group' context menu item.

Only occurs when the "enable new badges" flag is enabled.

Bug: 1098731
Change-Id: I75bb992c7f4d50c7c2bdac506782133e86a95fab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264253
Commit-Queue: Dana Fried <dfried@chromium.org>
Reviewed-by: Connie Wan <connily@chromium.org>
Reviewed-by: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782705}

chrome/browser/ui/tabs/tab_menu_model.cc

@@ -54,6 +54,7 @@ void TabMenuModel::Build(TabStripModel* tab_strip, int index) {
       AddItem(TabStripModel::CommandAddToNewGroup,
               l10n_util::GetPluralStringFUTF16(
                   IDS_TAB_CXMENU_ADD_TAB_TO_NEW_GROUP, num_affected_tabs));
+      SetIsNewFeatureAt(GetItemCount() - 1, true);
     }
 
     for (size_t index = 0; index < affected_indices.size(); index++) {