Chrome-like omnibar in Mozilla Firefox

Solution 1:

A blog from Mozilla has already shown how to Combine Your Firefox Search Bar and Address Bar since 2013, suggesting the Foobar add-on

The Foobar add-on lets you integrate the functionality of the search bar into the address bar, making searching and navigation quicker and easier for those who like a combined experience.

For more suggestions see Combine Firefox Address Bar and Search Bar into One Like Chrome

However you can already search from the address bar without a keyword even before that, since at least 2010. There's also a blog from Mozilla in 2012 talking about Easy Awesome Bar Search. If you don't want to see the search bar just right click on the toolbar > customize and remove the search bar. See

• Search the web from the address bar
• How To Use Firefox 4's "Awesome Bar" To Make Search Faster

Later in Firefox 57 Mozilla has turned off the search bar by default, with an option to change between the two layouts

• Change your default search settings in Firefox
• Add or Remove Search Bar in Firefox