Issue 4783 - Use Port API for the messageResponder

background.js

Index: background.js
diff --git a/background.js b/background.js
index fa78123054da5bb29352923c3496ec8a049eecde..59e1a13b93b4bdd5a3f92c58c0f8354c1cc18e3a 100644
--- a/background.js
+++ b/background.js
@@ -337,6 +337,58 @@
     reinitialized: params.filterlistsReinitialized
   };
 
+  modules.messaging = {
+    port: {
+      _eventEmitter: new EventEmitter(),

[Sebastian Noack, 2017/01/16 15:00:03]

Couldn't you do it like that:

  modules.messaging = {
    port: new EventEmitter()
  };

  window.addEventListener("message", event =>
  {
    // code from patch set #2 here but simply using
    // modules.messaging.port._listeners instead of messageListeners
  });

This way we wouldn't need to wrap the EventEmitter, neither do we export
private/prefixed APIs.

[kzar, 2017/01/16 15:16:31]

Done.

+      on(name, callback) { this._eventEmitter.on(name, callback); },
+      off(name, callback) { this._eventEmitter.off(name, callback); },
+      _onMessage(event)
+      {
+        if (event.data.type != "message")
+          return;
+        let message = event.data.payload;
+        let messageId = event.data.messageId;
+        let sender = {
+          page: new ext.Page(event.source)
+        };
+
+        function reply(message)
+        {
+          event.source.postMessage({
+            type: "response",
+            messageId: messageId,
+            payload: message
+          }, "*");
+        }
+
+        let port = modules.messaging.port;
+        let listeners = port._eventEmitter._listeners[message.type];
+        if (!listeners)
+          return;
+
+        for (let listener of listeners)
+        {
+          let response = listener(message, sender);
+          if (response && typeof response.then == "function")
+          {
+            response.then(
+              reply,
+              reason => {
+                console.error(reason);
+                reply(undefined);
+              }
+            );
+          }
+          else if (typeof response != "undefined")
+          {
+            reply(response);
+          }
+        }
+      }
+    }
+  };
+  window.addEventListener("message", modules.messaging.port._onMessage);
+
   global.Services = {
     vc: {
       compare: function(v1, v2)