Google is rolling out a way to customize the apps and products you want to see in your Google navigation bar.
Google announced this on Google+ saying that this is rolling out over the next few weeks to everyone. Here is an animated GIF of how it will work.
Personally, I never use that bar but maybe I should?
This is what Google said:
Now you can get to your favorite Google products even faster by customizing how they appear in your Google bar. Just drag and drop to rearrange the apps and bring your favorite products to the top.
You can also easily add Google products that aren’t part of the Google bar, like Google Keep and Google Scholar. Learn more: http://goo.gl/hw2cri
We're rolling this out over the next couple weeks, so please hold tight if you aren't seeing it yet.
Forum discussion at Google+.