Bug 1545340 - Hide Picture-in-Picture toggle on <audio controls/> elements. r=jaws

Depends on D27951

Differential Revision: https://phabricator.services.mozilla.com/D28016

--HG--
extra : moz-landing-system : lando

toolkit/content/widgets/videocontrols.js

@@ -270,7 +270,9 @@ this.VideoControlsImplWidget = class {
           this.setShowPictureInPictureMessage(true);
         }
 
-        if (!this.pipToggleEnabled || this.isShowingPictureInPictureMessage) {
+        if (!this.pipToggleEnabled ||
+            this.isShowingPictureInPictureMessage ||
+            this.isAudioOnly) {
           this.pictureInPictureToggleButton.setAttribute("hidden", true);
         }