[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 e0d6ac806894f803e4c0f9c3f0dc0f1dc7d10c7b..01a06ac19d93fc8c600275b2ceda5462766e4688 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;
 }