This article explains how to make Gmail's unread message count more visible in tabs. This tweak will display a count of unread messages over the Gmail icon in your Chrome tab. This setting is most useful if you keep your inbox open in a smaller, pinned window, or if you frequently have too many tabs open to see the count in the header.

To move the unread message count to the front of the Gmail page title and make it visible in background tabs or collapsed and minimized windows, do the following:

In your Gmail inbox, select Settings (gear icon).

Select Show all settings.