Implement receiver action listeners

ext/src/lib/loadSender.ts

@@ -4,6 +4,7 @@ import logger from "./logger";
 import { stringify } from "./utils";
 
 import { ReceiverSelection
+       , ReceiverSelectionActionType
        , ReceiverSelectorMediaType } from "../background/receiverSelector";
 
 import ShimManager from "../background/ShimManager";
@@ -25,6 +26,10 @@ export default async function loadSender (opts: LoadSenderOptions) {
         return;
     }
 
+    if (opts.selection.actionType !== ReceiverSelectionActionType.Cast) {
+        return;
+    }
+
     switch (opts.selection.mediaType) {
         case ReceiverSelectorMediaType.App: {
             const shim = ShimManager.getShim(opts.tabId, opts.frameId);