Issue 6440 - Use long-lived connections to listen to extension events

ext/content.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 41 matching lines @@
   ext.backgroundPage = {
     _sendRawMessage(message)
     {
       if (messageQueue)
         messageQueue.push(message);
       else
         backgroundFrame.contentWindow.postMessage(message, "*");
     }
   };
 
-  /* Polyfills */
+  /* Message passing */
 
   if (!("runtime" in browser))
     browser.runtime = {};
 
   browser.runtime.sendMessage = (message, responseCallback) =>
   {
     let messageId = ++maxMessageId;
 
     ext.backgroundPage._sendRawMessage({
       type: "message",
@@ skipping 16 matching lines @@
       resolvePromise = responseCallback;
     }
     else
     {
       return new Promise((resolve, reject) =>
       {
         resolvePromise = resolve;
       });
     }
   };
+
+  function postMessage(msg)
+  {
+    ext.backgroundPage._sendRawMessage({
+      type: "port",
+      name: this._name,
+      payload: msg
+    });
+  }
+  ext._Port.prototype.postMessage = postMessage;
+
+  function connect({name})
+  {
+    ext.backgroundPage._sendRawMessage({type: "connect", name});
+    return new ext._Port(name);
+  }
+  browser.runtime.connect = connect;
 }());