Fix metal external texture

Adlai-Holler · Adlai-Holler · commit 61e43f6e7dcc · 2020-07-24T11:11:06.000-04:00
diff --git a/shell/platform/darwin/ios/ios_external_texture_metal.mm b/shell/platform/darwin/ios/ios_external_texture_metal.mm
@@ -6,6 +6,7 @@
 
 #include "flutter/fml/logging.h"
 #include "third_party/skia/include/gpu/GrBackendSurface.h"
+#include "third_party/skia/include/gpu/GrDirectContext.h"
 #include "third_party/skia/include/gpu/mtl/GrMtlTypes.h"
 
 namespace flutter {
