Refactoring DownloadManager::DownloadURL to add proper annotation.

components/download/content/download_driver_impl.cc

Index: components/download/content/download_driver_impl.cc
diff --git a/components/download/content/download_driver_impl.cc b/components/download/content/download_driver_impl.cc
index 0d1d2811430ef5cc79a42201106575d270f3b872..17f684008564bfa5345120187580aeef7b603e20 100644
--- a/components/download/content/download_driver_impl.cc
+++ b/components/download/content/download_driver_impl.cc
@@ -81,7 +81,9 @@ bool DownloadDriverImpl::IsReady() const {
   return client_ && download_manager_;
 }
 
-void DownloadDriverImpl::Start(const DownloadParams& params) {
+void DownloadDriverImpl::Start(
+    const DownloadParams& params,
+    const net::NetworkTrafficAnnotationTag& traffic_annotation) {
   DCHECK(!params.request_params.url.is_empty());
   DCHECK(!params.guid.empty());
   if (!download_manager_)
@@ -106,7 +108,8 @@ void DownloadDriverImpl::Start(const DownloadParams& params) {
   download_url_params->set_method(params.request_params.method);
   download_url_params->set_file_path(file_dir_.AppendASCII(params.guid));
 
-  download_manager_->DownloadUrl(std::move(download_url_params));
+  download_manager_->DownloadUrl(std::move(download_url_params),
+                                 traffic_annotation);
 }
 
 void DownloadDriverImpl::Cancel(const std::string& guid) {