Bring back the URLLoader from the old Mandoline network service.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index b19e1c909cfad9d361e15bd416db330065745824..9e4bcd4fd6421216113af4b8f19b30c6a89d3661 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -1388,6 +1388,7 @@ test("content_unittests") {
     "../common/service_manager/service_manager_connection_impl_unittest.cc",
     "../common/service_worker/service_worker_utils_unittest.cc",
     "../common/webplugininfo_unittest.cc",
+    "../network/url_loader_unittest.cc",
     "../public/test/referrer_unittest.cc",
     "../renderer/android/disambiguation_popup_helper_unittest.cc",
     "../renderer/bmp_image_decoder_unittest.cc",
@@ -1482,6 +1483,7 @@ test("content_unittests") {
     "//content/browser/speech/proto",
     "//content/child:for_content_tests",
     "//content/gpu",
+    "//content/network",
     "//content/public/browser",
     "//content/public/child",
     "//content/public/common",