[MPRIS Data Engine] Ignore non-standards compliant players

Authored by broulik on Aug 7 2019, 9:43 AM.

Description

[MPRIS Data Engine] Ignore non-standards compliant players

Properties like Identity, SupportedUriSchemes, SupportedMimeTypes are mandatory.
Ignore the player if it's clearly violating the spec.

CHANGELOG: Players not compliant to MPRIS specification will no longer work with Media Controller applet.

Differential Revision: https://phabricator.kde.org/D22596