This new feature is called Global Media Controls (GMC) and has just been enabled in the experimental version of Chrome Canary browser. Specifically, the new control button appears on the right side of the address bar, and when clicked, it displays a pop-up window sliding down allowing users to stop or resume playing current multimedia content.
To activate this feature, you need to have the latest version of Chrome Canary. To do so, the first thing you should do is download this version from the following link:
Chrome Canary
And in order to use the Global Media Controls button, you only need to type the following link in the Chrome Canary address bar
chrome://flags/#global-media-controls
Activate the option as shown in the image and then restart the browser
This way, the new button will appear for you to pause or resume multimedia content.
