Currently we hook this using request's extra data that is plumbed in RenderFrameImpl::WillSendRequest, for, e.g. Blob. (Reference: https://codereview.chromium.org/2925903004/)
This could probably directly plumbed when we set-up / create URLLoader without going through extra data. Also it'd be better to have a generalized, common mechanism for this.
Comment 1 by bugdroid1@chromium.org
, Jun 29 2017