Steps to reproduce the issue

1. On a site with publicize disabled, and without URL verified via Google...
2. Go to Jetpack's "Traffic" settings
3. Click "Verify with Google"

What I expected

Login in popup window

What happened instead

Blank popup window

This appears to be occurring because Publicize registers a "sharing" menu, and the Keyring Service Helper requires that menu_page_url( 'sharing', false ) is hooked in order to render the "connect" urls. Unfortunately, that menu is only hooked when Publicize is enabled.

I recommend we always hook that URL if we are going to depend on it from multiple modules.