Copy some x509_certificate_model_nss functions to src/chromeos (reland)

Currently the Chrome OS network configuration UI is in src/chrome.

We want to move this to Settings UI which uses the networkingPrivate
extension API which is implemented in src/chromeos.

For network configuration we need to provide a list of available
certificates, including their display names, so we will need to
duplicate much of the logic in CertLibrary.

This is some initial cleanup work which removes the CertLibrary
dependency on chrome/common/net/x509_certificate_model_nss.cc
(which in turn depends on chrome/third_party/mozilla_security_manager
and contains significantly more code than CertLibrary needs and
would be difficult to migrate out of src/chrome).

It also removes some unnecessary src/chrome dependencies, and modifies
onc_certificate_importer_impl_unittest.cc to use the new helper method
instead of its own copied version of GetCertType.

BUG=380937
R=afakhry@chromium.org
TBR=emaxx@chromium.org, mattm@chromium.org, pmarko@chromium.org, tbarzic@chromium.org

Original CL: https://codereview.chromium.org/2871993005

Review-Url: https://codereview.chromium.org/2886913004 .
Cr-Commit-Position: refs/heads/master@{#472930}
7 files changed