GitLab

Right now, SSLBlockingPage has both overridable_ and strict_enforcement_. 
This CL collapses both into overridable_, so that we only need to check one. 
However, strict_enforcement_ also remains on its own because it is checked 
separately in one place.

BUG=
R=palmer@chromium.org

Review URL: https://codereview.chromium.org/448163002

Cr-Commit-Position: refs/heads/master@{#288456}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288456 0039d316-1c4b-4281-b951-d872f2087c98