chrome://inspect: Show 'Offline' in place of the device name while it is not authenticated

BUG=None
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/29363007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230723 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230723