Fix and refactor downloaded file handling in the loading stack

content/common/url_loader.mojom

Index: content/common/url_loader.mojom
diff --git a/content/common/url_loader.mojom b/content/common/url_loader.mojom
index e797c7e1a15e40c696680d3c063e5eed74b8e73f..74634bc7c94b89b020da060de44a7f638786d340 100644
--- a/content/common/url_loader.mojom
+++ b/content/common/url_loader.mojom
@@ -25,9 +25,17 @@ interface URLLoader {
   Cancel();
 };
 
+interface DownloadedTempFile {
+  // Cleans up a downloaded temporary file created for 'download_to_file' case
+  // of resource loading.
+  Release();
+};
+
 interface URLLoaderClient {
-  // Called when the response head is received.
-  OnReceiveResponse(URLResponseHead head);
+  // Called when the response head is received. |downloaded_file| is non-null on
+  // the 'download_to_file' case. Call DownloadedTempFile::Release() once the
+  // resource load has completed and the client finished its clean up.
+  OnReceiveResponse(URLResponseHead head, DownloadedTempFile? downloaded_file);
 
   // Called when some data from a resource request has been downloaded to the
   // file. This is only called in the 'download_to_file' case and replaces