By using the theme-color meta tag, you set a toolbar color in Chrome on Android 5.0 and up. This color will then be used in the app drawer as well and by using a color, your website can stand out and be recognized immediately.
Add the code, as found below, in your <head> of your HTML file. If you use a CMS, find the appropriate file to put this code in. If you use WordPress, this should be in header.php.
<meta name="theme-color" content="#168dd9">
Change the content value to anything you want, as long as it is valid. Don’t forget to also provide a high resolution (192×192 pixels should do it) favicon for Chrome to use.