Is this the same thing killing the HTTPAuthDialogTest.ShowForHttpsProxy test?  receivesCredentialSecurely is not being set on NSUrlProtectionSpace in the text for https urls.

No, certificateChain is not used for showing Http Auth dialog.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/049741269398bcc7c2b9aaf309d175d1fac9d90b

commit 049741269398bcc7c2b9aaf309d175d1fac9d90b
Author: eugenebut <eugenebut@chromium.org>
Date: Tue Jul 26 15:50:17 2016

[ios] Use -[WKWebView serverTrust] instead of certificateChain on iOS 10.

|certificateChain| WKWebView method is deprecated on iOS 10 and
|serverTrust| must be used instead.

BUG= 628699 

Review-Url: https://codereview.chromium.org/2151693008
Cr-Commit-Position: refs/heads/master@{#407812}

[modify] https://crrev.com/049741269398bcc7c2b9aaf309d175d1fac9d90b/ios/web/net/crw_ssl_status_updater.h
[modify] https://crrev.com/049741269398bcc7c2b9aaf309d175d1fac9d90b/ios/web/net/crw_ssl_status_updater.mm
[modify] https://crrev.com/049741269398bcc7c2b9aaf309d175d1fac9d90b/ios/web/net/crw_ssl_status_updater_unittest.mm
[modify] https://crrev.com/049741269398bcc7c2b9aaf309d175d1fac9d90b/ios/web/web_state/ui/crw_web_controller.mm