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

url/BUILD.gn

 # Copyright (c) 2013 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")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
@@ skipping 100 matching lines @@
       "//base/third_party/dynamic_annotations",
     ]
   }
 }
 
 # TODO(dpranke): crbug.com/360936. Get this to build and run on Android.
 if (!is_android) {
   test("url_unittests") {
     sources = [
       "gurl_unittest.cc",
+      "mojo/url_gurl_struct_traits_unittest.cc",
       "origin_unittest.cc",
+      "run_all_unittests.cc",
       "scheme_host_port_unittest.cc",
       "url_canon_icu_unittest.cc",
       "url_canon_unittest.cc",
       "url_parse_unittest.cc",
       "url_test_utils.h",
       "url_util_unittest.cc",
     ]
 
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
     deps = [
       ":url",
       "//base",
-      "//base/test:run_all_unittests",
+      "//base/test:test_support",
+      "//mojo/edk/system",
+      "//mojo/edk/test:test_support",
       "//testing/gtest",
       "//third_party/icu:icuuc",
+      "//url/mojo:test_url_mojom_gurl",
     ]
   }
 }