Add a ListModel::Move.

ui/app_list/apps_grid_view.cc

Index: ui/app_list/apps_grid_view.cc
diff --git a/ui/app_list/apps_grid_view.cc b/ui/app_list/apps_grid_view.cc
index ef1476487b518b9ddff488bbae0266f6e8e70e06..bbb414c578066d3aa2ef2bacfe0da68eaacaf697 100644
--- a/ui/app_list/apps_grid_view.cc
+++ b/ui/app_list/apps_grid_view.cc
@@ -325,6 +325,10 @@ void AppsGridView::ListItemsRemoved(size_t start, size_t count) {
   SchedulePaint();
 }
 
+void AppsGridView::ListItemMoved(size_t index, size_t target_index) {
+  NOTREACHED();
+}
+
 void AppsGridView::ListItemsChanged(size_t start, size_t count) {
   NOTREACHED();
 }