Use app list item shadow for app list folders.

ui/app_list/app_list_item.cc

Index: ui/app_list/app_list_item.cc
diff --git a/ui/app_list/app_list_item.cc b/ui/app_list/app_list_item.cc
index 0cac35a02364a348a35260588c55bd8714af7ce4..d0daa271c7a708dc758e9bf837f8ff34e1054dc6 100644
--- a/ui/app_list/app_list_item.cc
+++ b/ui/app_list/app_list_item.cc
@@ -11,7 +11,6 @@ namespace app_list {
 
 AppListItem::AppListItem(const std::string& id)
     : id_(id),
-      has_shadow_(false),
       highlighted_(false),
       is_installing_(false),
       percent_downloaded_(-1) {
@@ -21,9 +20,8 @@ AppListItem::~AppListItem() {
   FOR_EACH_OBSERVER(AppListItemObserver, observers_, ItemBeingDestroyed());
 }
 
-void AppListItem::SetIcon(const gfx::ImageSkia& icon, bool has_shadow) {
+void AppListItem::SetIcon(const gfx::ImageSkia& icon) {
   icon_ = icon;
-  has_shadow_ = has_shadow;
   FOR_EACH_OBSERVER(AppListItemObserver, observers_, ItemIconChanged());
 }