What steps will reproduce the problem?
(1) Visit http://csreis.github.io/tests/cross-site-iframe.html.
(2) Disconnect the network.
(3) In DevTools, run: navFrame("https://chrome.google.com/webstore")

What is the expected result?
The network error page loads in the subframe.

What happens instead?
The top-level renderer is killed.  This is because the error page tries to commit in the parent frame's process while using the Chrome Web Store URL as the last committed URL, and so that process is killed by the CWS CanCommitURL check in RenderFrameHostImpl::OnDidCommitProvisionalLoad.

Note that for CWS, this happens regardless of any OOPIF modes.  Once we start locking down URLs and origins that can commit with OOPIF modes, we'll likely hit this more widely.  This is another manifestation of our well-known problems with error pages, similar to issues  622385  and 560511.