Bug 1568216 - Disable context menu for Picture-in-Picture player window. r=JSON_voorhees

Differential Revision: https://phabricator.services.mozilla.com/D47785

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

toolkit/components/pictureinpicture/content/player.js

@@ -43,7 +43,14 @@ function setIsPlayingState(isPlaying) {
  * events for updating state.
  */
 let Player = {
-  WINDOW_EVENTS: ["click", "keydown", "mouseout", "resize", "unload"],
+  WINDOW_EVENTS: [
+    "click",
+    "contextmenu",
+    "keydown",
+    "mouseout",
+    "resize",
+    "unload",
+  ],
   mm: null,
   /**
    * Used for resizing Telemetry to avoid recording an event for every resize
@@ -134,6 +141,11 @@ let Player = {
         break;
       }
 
+      case "contextmenu": {
+        event.preventDefault();
+        break;
+      }
+
       case "keydown": {
         if (event.keyCode == KeyEvent.DOM_VK_TAB) {
           this.controls.setAttribute("keying", true);