Refactoring DownloadManager::DownloadURL to add proper annotation.

components/download/content/download_driver_impl.cc

 // Copyright 2017 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 "components/download/content/download_driver_impl.h"
 
 #include "components/download/internal/driver_entry.h"
 #include "content/public/browser/download_interrupt_reasons.h"
 #include "content/public/browser/download_url_parameters.h"
 #include "content/public/browser/storage_partition.h"
@@ skipping 63 matching lines @@
 
   download_manager_->AddObserver(this);
   if (download_manager_->IsManagerInitialized())
     client_->OnDriverReady(true);
 }
 
 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_)
     return;
 
   content::StoragePartition* storage_partition =
       content::BrowserContext::GetStoragePartitionForSite(
           download_manager_->GetBrowserContext(), params.request_params.url);
   DCHECK(storage_partition);
 
   std::unique_ptr<content::DownloadUrlParameters> download_url_params(
       new content::DownloadUrlParameters(
           params.request_params.url,
           storage_partition->GetURLRequestContext()));
 
   // TODO(xingliu): Handle the request headers from |params|, need to tweak
   // download network stack.
   // Make content::DownloadManager handle potential guid collision and return
   // an error to fail the download cleanly.
   download_url_params->set_guid(params.guid);
   download_url_params->set_transient(true);
   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) {
   if (!download_manager_)
     return;
   content::DownloadItem* item = download_manager_->GetDownloadByGuid(guid);
   // Cancels the download and removes the persisted records in content layer.
   if (item) {
     item->RemoveObserver(this);
     item->Remove();
@@ skipping 59 matching lines @@
   DCHECK(download_manager_);
   client_->OnDriverReady(true);
 }
 
 void DownloadDriverImpl::ManagerGoingDown(content::DownloadManager* manager) {
   DCHECK_EQ(download_manager_, manager);
   download_manager_ = nullptr;
 }
 
 }  // namespace download