We were unable to access the feature in Chrome Canary, but reports from users who have access to the button report that it is quite buggy and prone to crashing. Once you open the browser, type chrome://flags in the URL bar, then navigate to Global Media Controls (near the bottom) and select Enabled from the pull-down menu.
As previously stated, in tests conducted by BleepingComputer, this feature is in very early development and will crash often.
The feature will be named Global Media Controls, and has been rolled out to the latest version of Chrome's Canary distribution.
The Media Control Overlays works both with audio and video, per Engadget, although you can still expect some issues along the way on some sites. If you wish to try it yourself, though, you can download the Canary browser and test out the feature yourself. The button will be available on desktop versions for Windows, Mac and Linux. The global controls should work on any webpage that displays any video, although the feature is in testing for the time being.
(In fact, when Gizmodo tried the feature, it often crashed the entire browser seconds after just displaying the drop-down menu.) It now works with sites including Vimeo, Apple's podcasts, and Spotify, the Verge wrote. Once you have enabled it, you will see a play icon on the toolbar next to the URL bar.
It is an experimental feature for now and it is not certain that it will land in stable Chrome.
Google is adding a play/pause button to Chrome that will greatly simplify media control for users.
When the play button is clicked, it will cause an overlay to appear that contains playback controls such as play/pause, forward, and reverse.