[ash] Add TYPE_DIALOG and its item's LauncherContextMenu

ash/test/test_shell_delegate.cc

Index: ash/test/test_shell_delegate.cc
diff --git a/ash/test/test_shell_delegate.cc b/ash/test/test_shell_delegate.cc
index c89487ab426a9f46805a6a3337ba743f63838d74..bc9ebcf5646f5bc2c1d3c36af438bce81d85fb23 100644
--- a/ash/test/test_shell_delegate.cc
+++ b/ash/test/test_shell_delegate.cc
@@ -139,7 +139,10 @@ aura::client::UserActionClient* TestShellDelegate::CreateUserActionClient() {
   return NULL;
 }
 
-ui::MenuModel* TestShellDelegate::CreateContextMenu(aura::Window* root) {
+ui::MenuModel* TestShellDelegate::CreateContextMenu(
+    aura::Window* root,
+    ash::ShelfItemDelegate* item_delegate,
+    ash::LauncherItem* item) {
   return NULL;
 }