GitLab

Add logic to open options pages that open in tabs (embedded options
pages still to come). Add a test for the same.

BUG=529395
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2329443004
Cr-Commit-Position: refs/heads/master@{#419004}