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

extensions/renderer/resources/messaging.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // chrome.runtime.messaging API implementation.
 
   // TODO(kalman): factor requiring chrome out of here.
   var chrome = requireNative('chrome').GetChrome();
   var Event = require('event_bindings').Event;
   var lastError = require('lastError');
   var logActivity = requireNative('activityLogger');
   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');
 
   // The reserved channel name for the sendRequest/send(Native)Message APIs.
   // Note: sendRequest is deprecated.
   var kRequestChannel = "chrome.extension.sendRequest";
   var kMessageChannel = "chrome.runtime.sendMessage";
   var kNativeMessageChannel = "chrome.runtime.sendNativeMessage";
 
   // 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; }
 
   // Port object.  Represents a connection to another script context through
   // which messages can be passed.
   function PortImpl(portId, opt_name) {
     this.portId_ = portId;
     this.name = opt_name;
 
@@ skipping 36 matching lines @@
 
   PortImpl.prototype.destroy_ = function() {
     var portId = this.portId_;
 
     if (this.onDestroy_)
       this.onDestroy_();
     privates(this.onDisconnect).impl.destroy_();
     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
   // the C++ to avoid creating the javascript message for all the contexts that
   // don't care about a particular message.
   function hasPort(portId) {
     return portId in ports;
   };
 
   // Hidden port creation function.  We don't want to expose an API that lets
   // people add arbitrary port IDs to the port list.
   function createPort(portId, opt_name) {
     if (ports[portId])
       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;
   };
 
   // Helper function for dispatchOnRequest.
   function handleSendRequestError(isSendMessage,
                                   responseCallbackPreserved,
                                   sourceExtensionId,
                                   targetExtensionId,
                                   sourceUrl) {
@@ skipping 273 matching lines @@
 exports.Port = Port;
 exports.createPort = createPort;
 exports.sendMessageImpl = sendMessageImpl;
 exports.sendMessageUpdateArguments = sendMessageUpdateArguments;
 
 // For C++ code to call.
 exports.hasPort = hasPort;
 exports.dispatchOnConnect = dispatchOnConnect;
 exports.dispatchOnDisconnect = dispatchOnDisconnect;
 exports.dispatchOnMessage = dispatchOnMessage;