Add mojo struct traits for GURL so that it can be sent over mojoms.

url/mojo/gurl.typemap

Index: url/mojo/gurl.typemap
diff --git a/ui/views/mus/run_all_unittests_mus.cc b/url/mojo/gurl.typemap
similarity index 51%
copy from ui/views/mus/run_all_unittests_mus.cc
copy to url/mojo/gurl.typemap
index 4de8cdb1839a8f7617ce22c6454472e5c200eec0..3ce68b865c4f6c0c1941b8e1f7a775014819acb0 100644
--- a/ui/views/mus/run_all_unittests_mus.cc
+++ b/url/mojo/gurl.typemap
@@ -1,9 +1,14 @@
-// Copyright 2016 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.
-
-#include "ui/views/run_all_unittests.h"
-
-int MasterProcessMain(int argc, char** argv) {
-  return views::RunAllUnittests(argc, argv);
-}
+// Copyright 2016 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.
+
+{
+  "c++": {
+    "url.mojom.Url": {
+      "typename": "GURL",
+      "headers": [
+        "url/mojo/url_gurl_struct_traits.h"
+      ]
+    }
+  }
+}