Move Extension messaging port release functionality from JS to C++.

extensions/renderer/resources/messaging.js

Index: extensions/renderer/resources/messaging.js
diff --git a/extensions/renderer/resources/messaging.js b/extensions/renderer/resources/messaging.js
index e39795bdc0b1f00c4c8ec640ed7f2ed60a1d6dcf..c262222cda8a28b9e8b24de17d4d0e7946684c16 100644
--- a/extensions/renderer/resources/messaging.js
+++ b/extensions/renderer/resources/messaging.js
@@ -12,7 +12,6 @@
   var logging = requireNative('logging');
   var messagingNatives = requireNative('messaging_natives');
   var processNatives = requireNative('process');
-  var unloadEvent = require('unload_event');
   var utils = require('utils');
   var messagingUtils = require('messaging_utils');
 
@@ -25,10 +24,6 @@
   // Map of port IDs to port object.
   var ports = {};
 
-  // Map of port IDs to unloadEvent listeners. Keep track of these to free the
-  // unloadEvent listeners when ports are closed.
-  var portReleasers = {};
-
   // Change even to odd and vice versa, to get the other side of a given
   // channel.
   function getOppositePortId(portId) { return portId ^ 1; }
@@ -85,10 +80,7 @@
     privates(this.onMessage).impl.destroy_();
 
     messagingNatives.PortRelease(portId);
-    unloadEvent.removeListener(portReleasers[portId]);
-
     delete ports[portId];
-    delete portReleasers[portId];
   };
 
   // Returns true if the specified port id is in this context. This is used by
@@ -105,10 +97,6 @@
       throw new Error("Port '" + portId + "' already exists.");
     var port = new Port(portId, opt_name);
     ports[portId] = port;
-    portReleasers[portId] = $Function.bind(messagingNatives.PortRelease,
-                                           this,
-                                           portId);
-    unloadEvent.addListener(portReleasers[portId]);
     messagingNatives.PortAddRef(portId);
     return port;
   };