New Mojom Parser: Serialization.

mojom/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//testing/test.gni")
 
 group("mojom") {
   testonly = true
+  deps = [
+    ":tests",
+  ]
   if (is_linux && defined(go_build_tool) && go_build_tool != "") {
-    deps = [
-      "//mojom/mojom_parser",
-    ]
+    deps += [ "//mojom/mojom_parser" ]
   }
 }
+
+group("tests") {
+  testonly = true
+  deps = []
+  if (is_linux && defined(go_build_tool) && go_build_tool != "") {
+    deps += [ "//mojom/mojom_parser:serialization_test" ]
+  }
+}