Another missed flush call fix.

TBR:bsalomon@google.com
Change-Id: Ia9891916d41c2550b82e2e7222ec24bde7a939b6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290896
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/tools/skottie_ios_app/SkiaMetalContext.mm b/tools/skottie_ios_app/SkiaMetalContext.mm
index b49e360..f67d547 100644
--- a/tools/skottie_ios_app/SkiaMetalContext.mm
+++ b/tools/skottie_ios_app/SkiaMetalContext.mm
@@ -55,7 +55,7 @@
         return;
     }
     [viewController draw:rect toCanvas:surface->getCanvas() atSize:size];
-    surface->flush();
+    surface->flushAndSubmit();
     surface = nullptr;
 
     id<MTLCommandBuffer> commandBuffer = [fQueue commandBuffer];