Referencing a discussion from bugs.kde.org > plasma-browser-integration:
I was asking there whether it would be possible to add Chrome to the known media players list. This would make it possible to control Chrome playback via panel plugin in Xfce.
And it is already possible. However, a bug with Xfce4-pulseaudio-plugin is preventing it.
Quoting Kai from KDE:
Thanks for your suggestion!
I quickly checked the source code of the xfce pulseaudio plugin and from what I can tell there is an implementation bug that prevents it from working with this extension:
The DBus service we register is org.mpris.MediaPlayer2.plasma_browser_integration. The plugin uses the last part of the service name for looking up an application .desktop file, i.e. it would look for applications/plasma_browser_integration.desktop which doesn't exist.
What it should be doing instead is read the "DesktopEntry" property on the org.mpris.MediaPlayer interface which will return the browser's desktop entry (e.g. google-chrome) and then use this for matching. This is even greater of an issue if you consider that the service name could also have a PID suffix in case of multiple player instances, so this is something that should be fixed nonetheless.
Please file a bug report against XFCE, thanks!
Sean Davis referenced this bugreport in commit c02ece5b1fc415a5379fdd17133249fedc09f1c6
Enable reading DesktopEntry from DBUS, enabling Chromium playback with the plasma-browser-integration plugin (bug #15487)
Resolved in the above commit. Thanks for the detailed bug report!