1830: add media.eme.chromium-api.enabled

user.js

@@ -952,6 +952,7 @@ user_pref("media.gmp-widevinecdm.autoupdate", false);
 /* 1830: disable all DRM content (EME: Encryption Media Extension) [SETUP] ***/
 user_pref("media.eme.enabled", false); // Options>Content>Play DRM Content
 user_pref("browser.eme.ui.enabled", false); // hides "Play DRM Content" checkbox, restart required
+user_pref("media.eme.chromium-api.enabled", false); // (FF55+)
 /* 1840: disable the OpenH264 Video Codec by Cisco to "Never Activate"
  * and disable pings to the external update/download server
  * This is the bundled codec used for video chat in WebRTC ***/