DevTools: Consume middle click on tab header.

BUG=280756

Review URL: https://chromiumcodereview.appspot.com/23530006

git-svn-id: svn://svn.chromium.org/blink/trunk@156980 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove calls to to-be-deprecated Persistent functions.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23444025

git-svn-id: svn://svn.chromium.org/blink/trunk@156981 bbb929c8-8fbe-4397-9dbb-9b2b20218538