Decode the Dart message into a Dart_CMessage structure before calling the native port callback

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
index 63aafc6f2d3306f6dd0e46dd660811ad46ad70b0..abefc53ca19ff4ecc761b7b5ebd6105ead38b6c4 100644
--- a/runtime/vm/dart_api_impl_test.cc
+++ b/runtime/vm/dart_api_impl_test.cc
@@ -2889,7 +2889,11 @@ TEST_CASE(ImportLibrary5) {
 
 void NewNativePort_send123(Dart_Port dest_port_id,
                            Dart_Port reply_port_id,
-                           uint8_t* data) {
+                           Dart_CMessage* message) {
+  // Gets a null message.
+  EXPECT_NOTNULL(message);
+  EXPECT_EQ(Dart_CObject::kNull, message->root->type);
+
   intptr_t response = 123;
   Dart_PostIntArray(reply_port_id, 1, &response);
 }
@@ -2897,7 +2901,11 @@ void NewNativePort_send123(Dart_Port dest_port_id,
 
 void NewNativePort_send321(Dart_Port dest_port_id,
                            Dart_Port reply_port_id,
-                           uint8_t* data) {
+                           Dart_CMessage* message) {
+  // Gets a null message.
+  EXPECT_NOTNULL(message);
+  EXPECT_EQ(Dart_CObject::kNull, message->root->type);
+
   intptr_t response = 321;
   Dart_PostIntArray(reply_port_id, 1, &response);
 }