Return errors from the Mojo network service using an enum.

mojo/services/html_viewer/weburlloader_impl.cc

Index: mojo/services/html_viewer/weburlloader_impl.cc
diff --git a/mojo/services/html_viewer/weburlloader_impl.cc b/mojo/services/html_viewer/weburlloader_impl.cc
index 442099c183d75215b0d84185c115c41ecf8f10df..d2296d2eb65cac857fd3bce1a5800384374bcbae 100644
--- a/mojo/services/html_viewer/weburlloader_impl.cc
+++ b/mojo/services/html_viewer/weburlloader_impl.cc
@@ -123,7 +123,7 @@ void WebURLLoaderImpl::cancel() {
   URLResponsePtr failed_response(mojo::URLResponse::New());
   failed_response->url = mojo::String::From(url_);
   failed_response->error = mojo::NetworkError::New();
-  failed_response->error->code = net::ERR_ABORTED;
+  failed_response->error->code = mojo::NETWORK_CODE_ABORTED;
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
@@ -164,7 +164,7 @@ void WebURLLoaderImpl::OnReceivedError(URLResponsePtr url_response) {
   web_error.unreachableURL = GURL(url_response->url);
   web_error.staleCopyInCache = false;
   web_error.isCancellation =
-      url_response->error->code == net::ERR_ABORTED ? true : false;
+      url_response->error->code == mojo::NETWORK_CODE_ABORTED ? true : false;
 
   client_->didFail(this, web_error);
 }