After  crbug.com/884932  is fixed, browser initiated non-navigation requests will be hidden from extensions. This possibly allows for cleanup of several code sites-

- clientsX.google.com protection code in WebRequestPermissions::HideRequest.
- ChromeExtensionsAPIClient::ShouldHideBrowserNetworkRequest
- ChromeExtensionsAPIClient::ShouldHideResponseHeader (not sure about this).