Remove ShelfItemDelegate::IsDraggable; check for app list button.

ash/shell/window_watcher_shelf_item_delegate.cc

Index: ash/shell/window_watcher_shelf_item_delegate.cc
diff --git a/ash/shell/window_watcher_shelf_item_delegate.cc b/ash/shell/window_watcher_shelf_item_delegate.cc
index 9ac9c15bfa743ab7acbbc02183ff1cbf2453adb5..1a73dea7696f9881558e4010186d9baee3d86644 100644
--- a/ash/shell/window_watcher_shelf_item_delegate.cc
+++ b/ash/shell/window_watcher_shelf_item_delegate.cc
@@ -40,10 +40,6 @@ ShelfMenuModel* WindowWatcherShelfItemDelegate::CreateApplicationMenu(
   return nullptr;
 }
 
-bool WindowWatcherShelfItemDelegate::IsDraggable() {
-  return true;
-}
-
 bool WindowWatcherShelfItemDelegate::CanPin() const {
   return true;
 }