Download starts before Callback.Continue is called

[jfox]

My understanding of the way downloads work is that when CefBrowserHost::StartDownload is called, the code defined in DownloadHandler::OnBeforeDownload is executed, but the download shouldn't actually start until CefBeforeDownloadCallback::Continue is called. My code calls Continue outside of the OnBeforeDownload function after some additional processing is done, but I'm noticing that DownloadHandler::OnDownloadUpdated is being called before Continue is ever called, and the update info indicates that the download is in progress and has already read many bytes before Continue is ever called. This is problematic for us because we're relying on some additional processing to be done before the download actually starts. Is this behavior intentional, or this an issue with CEF?

[magreenblatt]

Your understanding is not correct, but understandable given the current OnBeforeDownload documentation. OnBeforeDownload is called from DownloadManagerDelegate::DetermineDownloadTarget in Chromium. The download will eventually be canceled if the CefBeforeDownloadCallback is not executed. This should be clarified in the OnBeforeDownload documentation.

[jfox]

Excellent, that explains a lof of the behaviour I've been seeing. I'm assuming there's nothing that can be done to delay the download once StartDownload is called then?

[magreenblatt]

I'm assuming there's nothing that can be done to delay the download once StartDownload is called then?

You could delay the download using a CefResourceRequestHandler callback like OnBeforeResourceLoad.