mash: Port mojo:ash_sysui's ContextMenuMus to mojo:ash.

ash/test/test_shell_delegate.h

Index: ash/test/test_shell_delegate.h
diff --git a/ash/test/test_shell_delegate.h b/ash/test/test_shell_delegate.h
index 49e41b0708c9149c33ecea6a0d749b855e2eb5cc..83dbcd13bda12980388b0b8513649cffae8551d5 100644
--- a/ash/test/test_shell_delegate.h
+++ b/ash/test/test_shell_delegate.h
@@ -49,7 +49,7 @@ class TestShellDelegate : public ShellDelegate {
   app_list::AppListPresenter* GetAppListPresenter() override;
   ShelfDelegate* CreateShelfDelegate(ShelfModel* model) override;
   SystemTrayDelegate* CreateSystemTrayDelegate() override;
-  UserWallpaperDelegate* CreateUserWallpaperDelegate() override;
+  WallpaperDelegate* CreateWallpaperDelegate() override;
   TestSessionStateDelegate* CreateSessionStateDelegate() override;
   AccessibilityDelegate* CreateAccessibilityDelegate() override;
   NewWindowDelegate* CreateNewWindowDelegate() override;