DCHECK is unnecessary in SimpleMenuModel::SetIcon.

Upon more detailed inspection of previous code, the DCHECK doesn't serve the same purpose and should be removed.

Bug: 1070132
Change-Id: Iaa1f175b3685c5e91f7910f7911839f4708525e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2145246Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Allen Bauer <kylixrd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758569}

ui/base/models/simple_menu_model.cc

@@ -287,9 +287,7 @@ void SimpleMenuModel::RemoveItemAt(int index) {
 }
 
 void SimpleMenuModel::SetIcon(int index, const ui::ImageModel& icon) {
-  Item* item = &items_[ValidateItemIndex(index)];
-  DCHECK(item->icon.IsEmpty());
-  item->icon = icon;
+  items_[ValidateItemIndex(index)].icon = icon;
   MenuItemsChanged();
 }