Use app list item shadow for app list folders.

ash/shell/app_list.cc

Index: ash/shell/app_list.cc
diff --git a/ash/shell/app_list.cc b/ash/shell/app_list.cc
index ec2071fe5293a17ccd3a6a3e91be6964767e8e2b..e2c9527fe8550e2bb11062cee77918034c402e2c 100644
--- a/ash/shell/app_list.cc
+++ b/ash/shell/app_list.cc
@@ -144,7 +144,7 @@ class WindowTypeShelfItem : public app_list::AppListItem {
 WindowTypeShelfItem::WindowTypeShelfItem(const std::string& id, Type type)
     : app_list::AppListItem(id), type_(type) {
   std::string title(GetTitle(type));
-  SetIcon(GetIcon(type), false);
+  SetIcon(GetIcon(type));
   SetName(title);
 }