GitLab

I'm going to be writing the renderer-side code to interface with the
NetErrorTabHelper, and it will need to understand DNS probe results, so move
that enum to common.

BUG=156415

Review URL: https://chromiumcodereview.appspot.com/11776031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175628 0039d316-1c4b-4281-b951-d872f2087c98