The latest Chrome builds in the dev channel now come with another addition to the right of the OmniBox, a zoom level icon.
This new icon is only enabled when you use the zoom feature, to either zoom in or zoom out. It's there to notify you that the page is being enlarged or shrunk.
It's also a shortcut to returning to the original size of the page. The addition should make it clearer to users that they are seeing a version of the page that's been altered, which would explain any problems they may encounter.
Since the zoom feature is persistent, users may forget they zoomed in on a page by the time they visit it again. The notification, with the zoom level, only shows up if you use a keyboard or mouse shortcut to change the zoom level.
If you do it from the menu, only the zoom icon will be visible, not the notification. You can zoom in and out via Ctrl and + or -, or, alternatively by pressing Ctrl and using the mouse wheel.