Add support for Mtl backend to DeferredDisplayListTest

Change-Id: Ie576bc8442e5a646c33191100be1be5f89d72290
Reviewed-on: https://skia-review.googlesource.com/c/189483
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/DeferredDisplayListTest.cpp b/tests/DeferredDisplayListTest.cpp
index 9347748..c8f0728 100644
--- a/tests/DeferredDisplayListTest.cpp
+++ b/tests/DeferredDisplayListTest.cpp
@@ -54,6 +54,10 @@
     const GrCaps* caps = context->priv().caps();
 
     switch (context->backend()) {
+#ifdef SK_METAL
+    case GrBackendApi::kMetal:
+        return caps->getBackendFormatFromColorType(ct);
+#endif
     case GrBackendApi::kOpenGL: {
         const GrGLCaps* glCaps = static_cast<const GrGLCaps*>(caps);
         GrGLStandard standard = glCaps->standard();
@@ -705,7 +709,6 @@
         GrBackendTexture backend;
         sk_sp<SkSurface> s = params.make(context, &backend);
         if (!s) {
-            params.cleanUpBackEnd(context, backend);
             continue;
         }