Is there a way to receive the same information as in IE Developer toolbar -> Network tab -> details -> initiator programmatically (from host of webbrowser control), or via javascript? I know about http header 'X-Download-Initiator', my question is about source, at the bottom of the screen.
No, as far as I know, this information is not available via any public API. You can set the feature control key so that the X-Download-Initiator
header is emitted, but that's the only initiator information that can be exposed.